I had a half point loss today, complete with silly endgame errors at the very end. I thought this would make a good game for comment, and I'd be grateful for any advice you have. I've looked over the game in crazy-sensei and left a few comments of my own in the sgf.

Hi jeromie,

AG would be helpful for evaluation here...

Doesn't feel like an AG move...

wonder about C13 hane... ( The game move feels not right, yea. )

Here's my two cents:

B9: I prefer hane, top is not very interesting since you have a solid but low position in the top-right

B17: I think you have to block C14. It threatens the cut and left side is much more interesting than the top anyway

B19: Exchange E18-E19 and then white has problems in his shape (e.g. you can then double hane at the left side)

B27: Just extend, leads to a big moyo game which shouldn't be bad for black

B33: A useless exchange that does nothing except loses a ko threat and a liberty. A liberty which would have been extremely important to prevent a cut at J17 in the variation where you extend to G14 instead of blocking at G15

B35: Probably extending at G14 is still better, although later you have to connect at J17 instead of J15 because of the bad exchange you made

B51: Yes, it's very good. Now white's center group should be easy to attack later since you have no weaknesses anyway

B53: You should play some kind of pincer (2-space high maybe?) to build your right side while preparing to attack white center group

B57: Feels like damage control (i.e. it would have been better to pincer to begin with) but it could still be a better move than extending normally. Even if white presses you low, it should be hard for him to build anything big in the center while his center group is so weak. Anyway, the pincering stone should probably be high to put more pressure on the white center group and better reduce white potential in the center.

B63: Great move. Builds your right side, puts pressure on white center group, reduces white center potential, and possibly even looks at the weakness at O5 or the invasion at M3

B65: I'd say this is your biggest mistake (and would be even if it blocked white cleanly). The kosumi might work better, but it's still very submissive. Playing such submissive moves should always feel really bad, and especially if your opponent has a weak group on the board. In this case I think you have to jump to N10 or N9 or something like that. After that it looks like white is in a lot of trouble, with a weak center group, P10 connection looking a bit weak, and weaknesses at O5 and M3. At least you should be able to destroy any white center potential in sente and then come back to protect your own territory, but more likely white will lose more than just center potential.

B81: Just jump to K10 directly without making all these bad exchanges. It looks like white might still have some trouble handling the center group. Although now it might be enough for white to just push from K9 and J9 and give up the center group to get a massive center.

Endgame:
-You should take O2 at some point, it's always your sente.
-B137 is really small (7 points in gote). You should play G3 and H2 (more or less sentes) and then C9 or something around there.

I think your biggest problem in this game that you seemed to forget that your opponent had a weak group while you were strong everywhere. A weak group on the board should affect almost everything that happens anywhere on the board, even if it never actually gets attacked. When your opponent has a weak group he usually has to play really timid and weak moves everywhere. If he doesn't, you have to think hard if there's a way to punish him for that. You on the other hand should always ask for a bit more than usual, play moves that might normally be overplays, but which your opponent can't punish as long as he has a weak group.

Thanks for the comments!

I agree that my biggest problem was not taking advantage of the weak white group in the center. I couldn't figure out how to effectively attack it, and I made several bad exchanges that allowed it to become strong enough to not be a real concern for white.