1. It's often easier to try in the morning after you've had some solid sleep and feel fairly rested.
2. Make sure you won't be interrupted or there won't be anything to distract you while you're attempting to have an OBE.
3. Let go of fear! You're entirely safe. And the more you believe that, the more true it becomes. Any dangers are truly illusions, but they can be quite frightening. However, you only attract them when you believe them to have power over you. What you believe, you manifest.
4. Always have a plan for what you want to do once you're having an OBE. This will help you to stay focused and present longer.
5. Read lots of books on astral projection/OBEs. The more you immerse yourself, the more it will become second nature.
6. Use strong mental commands once out-of-body. Your subconscious works best with demands rather than suggestions. Be clear and direct about what you are wanting.
7. I find that depriving my senses helps a lot too. Being in a dark room. Using ear plugs, keeping the room a comfortable temperature. Wearing soft comfortable clothes or a light blanket.
When you're relaxed enough and can no longer feel the difference between your body and the space around it, you're ready to try exiting your body. Here are several different ways you can try. See what works best for you.
1. Rolling out
2. Flipping backwards
3. Climbing a rope