Astral Projection Questions?

Lately I think I have been astral projecting randomly some nights.. My friends and I had talked about it a while back and i tried to practice it a couple times but could never get it to work so gave up... mind you i only did try like 3 or 4 nights:P I'm wondering has anyone actually ever done it? What happened? and I watched the dream Insidious or whtever tonight and is it true demons can take over your body if you get lost in astral? Thank you for your time.