OK guys, it's time to up the ante. I went from a slump of not getting anywhere near my prior high of 218,900 to getting 399,200! Previously I had never reached level 8; this time I got to level 11!
What do I credit this improvement to? Certainly some of it was luck of the draw - I didn't have a ton of wild barrels to deal with. But my last game was setting it for infinite lives and playing all the way to the kill screen. Honestly, I was really getting sick of playing that game since it took so long, but I think that helped to not only boost my skills, but boost my confidence as well. It seemed to me that the game simply doesn't get any harder after some low level number like 5 or something. It helps mentally knowing that the next level isn't going to be harder than prior levels. Also, I think I've finally made it over the hump of mastering the "new" approach to the elevator levels. I wouldn't say that I can do it in my sleep or anything, but I didn't lose a single life on elevators.
So if you're ever in a slump, I suggest playing with the infinite lives cheat and play all the way to the kill screen (be sure you have 2 hours to spend!). Try your best to play as if you didn't have infinite lives (it's hard to play exactly the same, but after all, you're trying to improve your skills here). I would say this approach is probably only effective if you've already mastered barrel control and are at least pretty good at getting past the elevator levels (not counting the 1st 2 of course). After all, you want to boost your confidence and skills, not get bogged down on an elevator screen, dying a dozen times trying to get past the springs!