6: Not bad - the high corner stone likes to have a long extension along the side (especially because if B invades the corner, you'll have a wall facing this stone). But it would be even better if you played it one space further out, at Q10 or R10. And it would be even better if you played R14 first to force a response, then jumped back to Q10.

12: Not great. Consider how this stone stands in relation to the two corners. W's group in the lower left is low, and has access to half of the corner: that means it is safe (so it doesn't need an extension to live) and has little potential for development (so it doesn't want an extension to profit). W's stone in the lower left has a nice side extension already at R9 (and it doesn't necessarily need a second one), but doesn't have any control over the corner. That means that L3 doesn't seem big with respect to either adjacent corner. On the bottom side, a move at P3 or O3 seems bigger. On the board as a whole, playing K16 to break up B's top is very large.

15: B is playing a second-line move with no tactical purpose. Surely a third-line move would strike a better balance between protecting the corner and projecting power into the side.

24: This is a mistake. Now B can atari R5. If you were reluctant to sacrifice R2, you should have simply extended to R6 first.

32, 34, 36: In terms of stabilizing your upper group, L17 seems bigger (taking firm control of a chunk of the side). In terms of staking out control of the center, E6 seems bigger - this is a point that both sides badly want to expand a side territory towards the center, and thus is double important (defense and offense at the same time.)

You also have a neat trick at R8: after you play R8, if B plays P7 or something with the aim of not getting squeezed in, you can play S4 and take back the corner; if he plays S7 to protect the corner, you can play Q7 and seal him in. Once B plays P7 himself, though, it's too late.

40: Consider what you're trying to do here. It looks like you're trying to separate two groups but the groups in question must be P7 and J9, which are 5 spaces apart already. They're also both independently alive. So separating them doesn't accomplish much, and even if you did need to separate them you don't need such a slow, crawling move; L6 or something would be the same idea on a faster scale. In fact, what you want is something like E6 or N6 to develop your side territory.

(Alternatively, you could try to reduce black's areas, with an eye to invading.)

58: Locally, your profit is something like 8 points. If you had played O6 instead of M7, or one of the other center moves, you could have hoped for 16 or more.

82: You want to try this sort of invasion before encouraging B to play N15, O15, P14, Q14, and R13.

118: No need to capture this. If B captures, you can immediately recapture (a snapback). Capturing here is not only wasting a move, it's -1 point.

148: Note that B can just respond at E18, and you can never reconnect your stones. E18 first is much better.

186: Why not T12? It's one point better.

191: It's worth thinking about whether the implicit threat behind Bt12 is better than the threat behind Ws1. If you had ignored T12 and played S1, black would have responded at S3 immediately, giving you a swing of 3 points.

196, 202: Compare these two moves to Ws14. If you play Ws14 and black responds, you make 1 point and it's your turn again. If you play Ws14 and black ignores, you capture three stones and then either black recaptures or W can make two points of territory. That's an awfully good followup, isn't it? So play that before you play the smaller moves at O5 and L4, since you can get all three of them.