Stated Perfectly by Raphael. If I might add, before you get settled to lay still, answer your bodies needs. By this I mean, scratch whatever is itching, roll on your good side, get comfortable basically. Try doing whatever you would normally do before falling asleep on a regular night/nap, and just put as little attention or effort into staying away. Remember, mind awake, body asleep. Your mind is always working and awake while you sleep, but you just need to get a hold of it and stay conscious just enough to know that your trying to Lucid Dream. Try the archives on DreamViews with more information on Sleep Paralysis if you see it necessary.

If I may recommend something that could help: Sleep Paralysis Tutorial - Dreamviews Lucid Dreaming Community & Resource

Good Luck,
~CV