Below is a response I made to another poster about a month ago or so on a similar question:
First off, I know most people feel vibrations prior to leaving their physical bodies, but I never do. So if you do feel the vibrations, then wait until after them to try and move your body.
But it sounds to me like you are not nearly relaxed enough. Your physical body should feel completely asleep. You should get to a stage where you don't even realize you have a body.. you can't feel it. After this stage, you remain still until you begin feeling your body again, but it feels light and floaty. For me, I always feel my arms first. I know mentally where they are positioned, but I feel them like they are bobbing gently in the air above and just outside of where they actually are. Almost like the feeling of letting your arms float in water -- the bobbing floaty sensation. When you reach this stage do NOT move anything. Don't even try to move anything. At this point, its just your arms that are loose. Eventually you'll feel the rest of your body begin to feel very light and floaty as well. At this point, still do NOT move.
When first learning to get out, its better to move slowly and cautiously because too much effort moves the physical body. When moving your etheric you don't need as much effort to move. It may help to stop and think about the way you move your arm, for example. While awake and not practicing for an OBE, consciously think of the way you move your arm, starting from the thought of actually moving it. Pay attention to the muscles in your body as you slow down the process. You should notice subtle changes in your mind and body as you think of moving your arm, then as your muscles in the upper shoulder begin to tense in preperation for movement, then as the muscles in your arm actually flex to move it. Do this repeatedly until you can identify the different nuances within your body at each stage. Then practice on stopping the movement at the point just before the muscles begin to tense in the shoulders. Up to that point is all of the effort you need to move your etheric body. If you focus on just isolating that sensation while awake, when you practice for an OBE and reach the stage of feeling light and floating, then apply this movement to your arm and you should feel it move somewhat slow, as if you were moving it underwater. This is great for starting. Keep at it and eventually you'll be able to move your etheric body without the risk of moving your physical body.