I echo what Aerospace101 said -
Increase your scan, and if you know you're in the chop, have a quick scan at least once every three seconds or so, and make an analysis as to the rate of change of altitude (I say it like this because the VSI is useless in turb, too much delay for the accuracy you want!) - if the altimeter's increasing, apply forward pressure gently, and continue increasing that forward pressure until it reverses, and what I find helps, is to fly the aeroplane as though it weren't turbulent at all. Don't fight it, pretend it's some big ass guy trying to swing punches at you, but you don't need to jump all over the place swinging back, just step from side to side smoothly.
Just try to relax, and you'll find you're more efficient, but in saying that, if you hit the rough stuff, deviations of +-50 feet are acceptable and probable, especially if you have a high workload as well.
Again, as the poster above mentioned, strive for perfection, fire the arrow at the ant and for sure you'll hit the anthill
