I've recently started thinking a lot more about moves when I'm off my bike. I think about the techniques I'm gonna need to learn and the movements my body will need to make and it's really paying off. I've never been able to tuck while gapping, so when I'm in bed shutting my eyes drifting off to sleep, I visualised tucking my legs up while gapping, a few days later I got out on my bike in my street, low and behold, I could do it, it wasn't perfect but the basic technique was there, and its going to make it easier in the long run to get it nailed.
Same with sidehopping, I've never been able to do it, I was in the shower one morning thinking about riding and the movement of my body and bike while sidehopping, and a few days later I was doing 26" to back wheel, might not seem like much but that went from not being able to sidehop at all, to being able to hit 20+ inches consistently. All I need to work on now is my preload technique and hopefully I'll start improving it.
So yeah, when you're not riding, visualise yourself doing the move, I've found just with those two things it helps shit loads.
But always remember this...
EDIT: Also, anger never helps, it just makes things worse, I often find myself getting frustrated riding walls that I could nail last summer, but because I've been off the bike for 9 months I haven't lost a lot of the little things like timing, and explosivness (funny how Chrilles advise is all of a sudden making sense to me). When this happens I'll try something else, or try the move on a smaller wall, once I've got it completely dialled, I'll go back to the bigger wall and can usually do it in a few attempts. Don't ever get mad, it's okay to get frustrated, but don't take it out on the bike.
People must look at me on rides and think I'm a spoilt rich kid or something, I've usually some of the best parts, I've always had CK hubs, well looked after bikes, etc. and people are going bigger and better than me on what are, in comparison, pieces of junk. But my mentality is as follows, if I buy the best things I can afford for my bike, then the only thing wrong, is me. I can't say, if only I had this part, or that part, I would be able to do it, it's all down to me, and I've found that if you have confidence in your bike, you will improve, and it will help raise the confidence in yourself.
After reading the thread in Bike Pics about Quackers new Koxx Boxx, the same thought popped into my head, he's riding one of the best bikes in the world, and if Vincent or Gilles or Giacomo got on his bike, they could still win competitions with it, so he knows it's a capable enough bike to with the world championships with, so if he can't land a tap, or a hook, then the only person he has to blame, is himself.
The machine is doing nothing wrong, it's the monkey operating it that can't get the move right. There's no point throwing your bike around because it's just going to end up damaging it and you're gonna have an even worse ride because you've popped a hose, or snapped something.
Just stay positive, stay calm, and spend time off the bike, thinking about things, and I reckon in a few weeks you'll have taps nailed.