I don't know what you're style is, but it's usually just where you have your pickup selector set. If you've got humbucking pickups try the last one. (closest to the bridge) That works for me. Other than that, try turning down your distortion.

like I said, I don't know what your style of playing is, but a lot of grunge/death/heavy metal freaks get all worked up about not having TONS OF SATURATED DISTORTION and "less is more." you'll have more control and you're palm muting won't sound so much like buckets of paint being splattered on a sidewalk.

Hope it helps. it helps me. lol.