This move is rather inefficient, as said. The A area is not very interesting since it's not a lot of potential to build territory anymore. Later, White doesn't really need to invade with a move like A (unless the situation is suitable). Rather, White could just poke from above with B,C,D,E,F etc and threaten A. If Black answers White has successfully gained a stone to reduce Black's influence. Pushing above is usually crude when Black is 4th line since it would help Black secure 4th line territory, which is usually very hard to defend in the first place.

Kamoro: "W plays a slow move, so I tenuki."

Indeed you are right. White made a very slow move. However, Black should answer this.

There is a good (yet crude) thumb rule for the opening: "Take the sides with the most space". It's pretty accurate, and this move follows the idea. However, this kind of move which Black makes is rather slow because it doesn't really put any pressure on White's top left corner. Black is just preparing to defend the A area and that's it. An approaching move like B would be much faster, have presence and still follow the thumb rule of "Taking the sides with the most space".

If you are curious about some details on this subject I have a Review I made for another 15k on this topic. You can find it here:

https://online-go.com/review/45847

This is a really good punishment by White. It prevents Black from approaching the top left corner on the left side.

Black is yet again playing too low. Why not aim for more territory with A when you have a 3rd line enclosing stone like B? (C is a better move in reality because it concerns 3-3 but I don't wanna discuss the invasion point again).

Kamoro: "Here I try to get influence in the center."

Okay that's a plan. However, White will just push at A, making the B area significantly stronger. Moreover, White stil has entry at C into the moyo and D is a very big move which still works for White. White could also just poke the moyo from the center.

Don't expect to make territory in the center. It's unpredictable. Try to secure the sides first instead.

Kamaro: "I don't want my opponent to have a wall blocking the larger half of the board, even if he is pushing from behind, so I hane"

That's very good thinking and the idea is correct. However, there are so many ways to poke this moyo as said. Also, Black has limited choices if White cuts at A since White can ladder the Black stone. I don't think it's good now though. White should hane at B instead and build her own moyo.

Kamoro: "Not sure if the cut point is a risk, but I fix it just in case."

It's strong! Usually the best moves are the moves which leaves no weakness and make sure we are connected. Similar, seperating your opponents stones and making them weaker is just as big.
Also, White's jump at A is easier to block now with B response.

This move really makes A a lot less useful.

If I were White I would just tenuki here. The atari is not dangerous. It would be better for Black to play A or B (not completely sure) before White takes complete control of the top. C is also a big move for Black since it's White's last chance to reduce Black's are by invading 3-3.

It's slow. Not sure what you are expecting in the center. White can just poke it with B,C,D. There is also the corner at A.

Kamoro: "In hindsight, I don't like this move. Even if he would have pushed up, he would get a whopping 1 point of territory. Better to play somewhere bigger."

If it wasn't for A and B this move would be a big move since it seals White in and grants influence on the left side. But it's just as you say, it's not very good on this board. You should just tenuki.

It's an odd move by White but regardless shes alive.

This is a really good way by White to reduce Blacks moyo. Poking whilst building her own influence towards the top. It's almost a textbook example of how you should make influence.

Kamoro: "Decided to respond to his invasion with an invasion of my own, while at the same time putting more influence in the lower middle."

Yes! It's much better than simply defending the moyo. However, it's not so good. Moves like A,B,C or even D are much bigger since they make actual big profit and more importantly prevents White from taking control over those spots (which would be a lot of territory for her). The top is still so wide and empty. It's easy to play there and make life. There is nothing you are 'invading' here.

Kamoro: "Went for the peep here."

How so? It's a bit aji-keshi. You ruin the chance to exploit White's fragile connection.

Overplay

Your moyo is so strong. A was the vital move here.

Kamoro: "Probably could have played at 1 in order to fatten up the capture/enclosure at 2. But for some reason I thought that if I didn't capture immediately, I'd be captured myself, which is of course a miscalculation."

It happends. As long as you realize your mistake it's already good.

Kamoro: "I decide to grab the corner while I still can. That last move was gote anyway."

Indeed. Also, that corner is big. However, after the sequence in the middle your moyo is practically enclosed. A is so much points, and it also threatens Black B later.

White blocks the wrong way.

This was not neccessary.

Kamoro: "Opponent has me in atari, but one move too late."

:^)

Not all stones are valueable. You need to ask yourself what purpose your or the opponents stone serve. So if we look at A. What purpose does it have? Disconnecting the B group? Hmm okay, but it seems it got a connection with C. So maybe it's not so important?

Remember the steps for killing? It seems to apply pretty well to White here. Here they are again:

1. Surround (Cut off the stones from the rest of the board)
2. Remove any space for the opponent to extend her base
3. Destroy eye shape

Step 1 is already complete. White is completely sealed in and cut off from the board.
Step 2 is somewhat done you could say since I intended it to mean the sides. 

So that leaves step 3. Perhaps a move like D would have been better since if you imagine White playing D it would starting forming eyes at the marked spots. This is your really strong area. White has nowhere to escape. Poke eye shape without hesitation nor fear!
I haven't read this, but I know White can't live because there is no escape, and no weakness to exploit. Judging this might take some experience though.

This is a really good sacrifice by White and also shows why A was a mistake. White gets a chance to gain shape.

A is easier for Black.

Mistake, but it's still fine.

Kamoro: "Gouging out the potential eye."

Strong! :-)

Connecting at A is more flexible shape. It makes sure you can connect to B as well.

A would be easier to play since White is aiming at B.

Kamoro: "Thought a mouth would be a secure connection. Unfortunately it puts me in gote and allows him to connect."

Yes... I think it's very slacky of you to not read it out. Discipline.

Just play A. White is connected. You are just reducing your own liberties and I think you know that you can't cut him anymore. It's really slack.

Kamoro: "This group is approaching the wall, where it can easily make a second eye. I decide to let this group live, but block off the bottom."

Yes, a wise descision! But you should've done it earlier instead of reducing your own liberties. There is some bad shape on the bottom now.

This is not very big. You need to ask yourself more which move is the largest, and then ask if there is anything even larger. E.g Imagine White blocking at A. It would be lot of territory she saves and it's sente. Thus A is so large for Black It would threaten to reduce even more afterwards with a move like B and Black is threatening to lean withC at the same time. The top left corner is also a concern since the D side is so solid already. White only needs to solidify the top and it would be difficult to make anything good in the top left corner.

This is kinda crue by White. Black could (and probably should) play away but...

It's a good move still since A was big. However, if you weren't aware of that then this is kind of slack.

A would still be larger than these moves.

It's so big. Black responded to White way too much in the bottom.

I am not sure how good this is. I would rather jump to A. But take it with a grain of salt.

You should've played keima to A instead. White will just block you now.

You don't have two eyes. A was vital.

Kamaro: "Taking the corner while it's still available."

Very good, but A is also extremely large.

A would be easier to keep connected. But still B is the only move.

It's really interesting. But it's so complicated and unpredictable.

I think these moves are really strong!

I am gonna stop the Review here. I am a bit too tired to continue. You are a player with a burning fighting spirit for the game. I don't even think a review was so neccessary because you will grow so fast anyway. I just know. I hope it will be useful still. o/

I have to use a forcing move in order to make two eyes.

Considering blocking this would make a mouth, that one point reduction was probably not worth gote.

Gotta make two eyes just in case. I'm still traumatized from when a player killed my corner enclosure because for the first few moves, I thought he was trying to make life in an area far too small to make life.

Now I have a ladder.

Decided to claim a few points in the left.

Here I'm trying to push the boundary as far back as I can.

Here I'm just hoping he blunders.

Again I'm hoping he blunders.

It's impossible for him to stop me from making two eyes here.

The server marked these stones as dead. I should have played it out because they were obviously alive, but I still would have lost by 7.5 points.

I am just experimenting here. No comments.

Missclick. Just A or B.

This is much easier to predict. You don't always have to put everything at stake.

This seems like a winning endgame sequence (of course, White A was sente all this time but I forgot).

Black can live but could've gained so much more.

This would be an ideal sequence.

White can't capture the entire group.

Not possible neither.

It gives White a little more reason to play this. Black ought to just tenuki again though.

Black can't cut...

Here is a way to split.

This is tricky

Question: Are the two marked stones important?

This doesn't work so well.

I think this would be easier

Like this, but hard to find.

I would like to know myself where White should play next (well, tenuki but you get what I mean).

If White here...

...you could play like this but...

...White will be satisfied reducing in sente and then play the large move in the widest area left on the board. Black's moyo didn't become so large in the end.

Knight's move (or Keima) is a rather fragile connection (good to keep in mind!). You could've cut (though it might not be the best move on the board atm) or just saved the aji for later.

It rather difficult for White. Also, Black gained some strength the cut White at A.

You should probe here first. If White connects A is not neccessary because the clamp at B can't connect underneath. If White KO just take the KO. You don't have to win it at all. You can always just got back and play A if you don't wanna fight it.

How about here?

Here White is gote since the A stone is not dangerous. Black is strong on both sides of the cut.

Normally this would be a good move but White is so thick on the right side...

White won't pincer Black because Black would take the corner. Black still has to help the A stone after this

It's slow. Next, White aims at A

White has a good technique here.

White can keep the corner. However, Black gets a solid group on the bottom side and sente to secure the corner. It's playable.

I was thinking about A but it's not very good. You could say it's a tricky play.

Also a solution, but it's gote

White falls for trick.

Missclick

Very good for Black.

Missclick :c

Black's tenuki is questionable...

With the stone at A, White can have a better go at this fight.

Approaching A or B wouldn't be 'approaching' moves anymore since White would be jumping straight into a pincer. They would be 'invasion' moves. This 3-3 is the only approaching move left and it's sente. It's very uncomfortable for Black since there are only low stones in the area. E.g if C was on the 4th line Black would block at D without hesitation since it would become a really strong moyo.

White can just take the corner then defend the top left. Black really doesn't get all that much. So many low stones.

If Black blocks this way now...

Wouldn't you want to be at B now?

After this move, Black's corner is secured. It's well worth over 20 points. There is more to it than just points though. It prevents White from playing A herself, which would make your B stone weak and rather useless. Also, White is so cramped. If White tenuki...

...Black could pincer White. White doesn't have enough space to make a base here and it would make a good attacking target. (A would be a better pincer by Black for complicated reasons, but I just want you to get the general idea).

Playing high here is much better. The reason is that the 3rd line stone works like an enclosure for the 4th line territory. The area at A is looking a lot larger and is something White can't neglect through the game. Later, Black could enclose with B. 
White can't poke from above with e.g B,C or D because it would help Black secure 4th line territory which is otherwise very fragile.
Also, there is no need to fear the invasion at A. Rather, playing like this is an invitation for White to invade so Black can get an attacking target (see continuation if you are curious about the details).

To demonstrate the invasion, lets play out this simple joseki. White wouldn't usually invade immediately because there are two ways into this area; The Corner and A. If Black secures one, White takes the other.

Please note that if Black didn't have A she couldn't have played away now. White would play B without hesitation, poking Black's 4th line territory but also threatening Black's base. It's not only just for this case. It's very popular to poke 4th line territory by approaching it on the 3rd line like B. C is also the same if you look carefully. It's one of many weaknesses a 4th line stone has. 
It's very difficult for Black to make a satisfying answer to B without A. I won't get into the complications but regardless, Black would have lot all potential to expand the bottom right corner group across the bottom side of the board, making more territory.

Lets say White invades here. It is much too early and a bad move. Black gets a free attacking target. Please note that attacking doesn't neccessarily mean 'attack to kill'. I forbid you of such greedy thinking. In Go, it's really difficult to secure solid points. Instead, we attack this stone with the purpose of 'Threatening' to kill.

There are some good steps for killing your opponents stones:

1. Surround (Cut off the stones from the rest of the board)
2. Remove any space for the opponent to extend her base
3. Destroy eye shape

Again, we are not killing but we are threatening to since we have so many stones surrounding White. Lets start with step 1:

A, though contradicting the proverb of "Do not attach to weak stones", is actually not a bad move here since it seems to follow step 1 pretty well. Also, in Go, it is usually very big if you can seal your opponent in. It means that the group will be cut off from the rest of the board and have significantly less potential and influence upon what's going on outside. However, since Black has the lower left corner, B seems to be a better choice since it seals White in better from the left (it is also a more severe attack).

White didn't really get a lot of points from invading Black. Instead, Black got some really strong influence and the A area is pretty much secured (whilst before this it could be invaded and reduced). What more, Black is sente which is usually the case when someone invades and you just attack them solidly. When they are alive you just play away. I hope you agree that Black seems far superior here.
You might think the influence is not very useful towards the right side. Actually Black has a good probe at B. But I am not gonna get into that.

Also good.

Also a really good result for Black. But it failed to seal White in completely and secure territory at A. It can be a bit tricky figuring out how to use the influence. Regardless, White didn't gain much profit, and Black is sente e.g Black could continue at B.