OK aditya,
Here's a trick that I've discovered. If I wake up in the middle of the night after getting several hours of rest, but not fully recharged, I get up and move around a little. Maybe get a drink of water, then lay back down and begin some visualization exercizes. These could be concentrating on each chakra up and down the spine visualizing the colors and meanings of each or maybe I envision myself getting out of bed and walking around and going outside for a walk. I try to visualize as accurately as possible. Then after 10 or 15 minutes of this, an OBE will occur. That's really all there is to it. My body has to be tired enough and my mind needs to be alert enough for it to happen.
Hope that helps.
With Peace,
Paul