I find that it's hard for me to push forward my technique. When strength/power/endurance in a specific area is limiting me, it's easy to find exercises that work the part that's weak or easily tired. If my mental game is weak, I just do a bunch of practice falls. But technique is harder. I've watched the Neil Gresham videos and I've relatively mastered the handful of flagging exercises he gives, but there's so many other techniques that I don't have simple drills for.
The obvious thing is to climb more. Boulders help me isolate out the technique aspects of climbing because I don't have to worry about endurance as much, but if I'm not careful this can just turn into unproductively strength/powering through climbs. So here are some things I've found that help me isolate out and train technique while bouldering:
Downclimbing Doing a motion backwards gives you an idea of where you want to end up and how to get there, so that you're properly balanced throughout the move, so I used to try to downclimb every boulder problem. I run into problems with this, though, because I find it's hard to remember how each motion felt going one direction while doing the other direction, since the forward and backward motions are so far apart.
Forward-Back-Forward To solve my problem with downclimbing, I decided to do each move forward once, backward once, and forward once before moving to the next move. This allows you to feel how a move feels in both directions, then immediately do the move forward, trying to integrate what you learned while it's fresh in your mind. You can do FBFBF or FBFBFBF if you want, although obviously the more times you repeat a move in each direction, the more this becomes an endurance exercise.
Pause Climbing Pause in the middle of each move, and fix any problems with your balance before touching the next hold. I find it's easy to fudge this, so I find it best if I count to a full 1 Mississippi, 2 Mississippi, 3 Mississippi before I touch. The counting can distract from balance, though.
Of these, FBF is by far the most effective for me.
Does anyone have any more training drills which focus specifically on technique?
* climb different kinds of rock than you have before.
* climb indoors at gyms with very creative routesetting.
* have somebody shoot video of you climbing different kinds of problems.
Down-climbing? I do lots and lots of it -- but that's because I just want to be really good at down-climbing (because it's essential for safety in on-sight soloing). I have not noticed that it helps my up-climbing technique.