So I've continued trying to play more aggressively, albeit it the slight worry in my mind of what I'll do when I get to the level of opponents who know how to handle such aggression. Recently I came up against such an opponent, as it seemed that nothing I tried worked, although I didn't realize it until several moves after the fact. Part of the problem is that while I played what I think are more daring moves, they also had the effect of leaving a possible weakness and having to figure out what to do if my opponent tries to exploit it:
The tenuki on
. I've always been uncomfortable about playing tenuki in response to an approach, as there's always the question of what to do when your opponent plays the double approach. I don't think I got that bad a result, although my reading couldn't figure out how much pressure I could have put on White to keep his two groups separate.The pincer attack on
. I know the sequence, and I know the result is that Black gets a wall while there's aji from the R14 stone I'm pincering. During the game, I couldn't figure out at all how to deal with that aji, and the result is spectualarly bad. 
Leela particularly hated when I played P15.Leela also hated my play at K17, which surprised me since I thought it was a good, aggressive reducing move.
Looks thin.
The attachment at E-17 looks good. Push White around a bit and then come back to enclose the bottom right corner. The three space extension is now passé. (Until maybe later in the game.)
The solid connection is no longer played. S-14, connecting underneath, is better.
Worried about the five Black stones in the corner being attacked? If you connect underneath you only have to worry about three stones, and White needs to cut to capture them. Still, this move is slow. Better the E-17 attachment. With this play and the three space extension, Black is falling behind.
Heavy. That helps. 
Strengthens White. Since White already has the N-04 stone, maybe better just to jump to O-03 right away, threatening P-05.
With Black strong on the right side, not a good plan.
Overplay.
Black is already strong here. Much better to use that strength to push up with O-04 and cut off the three White stones to the right. They will end up fighting in Black’s sphere of influence. 
O-04 is better.
Compounds the felony. Push and cut.
A clever play.
Not a bad idea. 
There is nothing to fear. The stand is good. Then after White C-06 or D-06, come back to peep at L-03.
The hane on top at F-04 is good.
Defensive. Better to build up some strength here with sente, starting with the attachment at F-17. Push White around a bit. Then, having already built up some strength on the bottom side, attack the White stones in the bottom right, starting with the jump to O-05, as Ed suggests.
is at one of the a points, you can play something like this:
pincers the 
stones. 
plays the two space jump. Then 
prevents that. After strengthening himself with sente, Black jumps into the center with 
. This move threatens 
Block at Q-14 and let White connect his two stones. You would not have had this problem if you had played S-14 earlier.