Astral Travel and Astral Projection are natural abilities that nearly everyone can develop. In fact, many people have had 'out-of-body' experiences and don't realize it. But before we go any further, we should clairify the terms. Astral Projection is projecting your concious mind out of your body into your spirit body or body of light. These are two of the most common terms I've heard used. Astral Travel is the art of travelling or going places once you are successfully out.
Another common question is whether or not Astral Projection and Astral Travel are dangerous. The answer would be no. These are natural abilities and as far as getting lost or getting stuck out of your body, you don't have to worry about that either. Staying out of your body is the hard part, not returning. A simple desire to return to your body will return you quite quickly. And if you are gone for a long time your body will pull you back when its needs demand it. For example if you get hungry or need to use the bathroom your body will pull you back, alerting your concious mind that there are matters to attend to.
Being harmed or injured during projection is another thing that you don't have to worry about. You might give yourself a shock or scare, but as far as injury goes, that's not in the cards. Of course your 'sleeping' or dormant body should be left in a safe place. Think of it as your body is sleeping while you are away. So a bed might or a comfortable chair might be a good place.
That should cover most of the basics. You can find my guide to Astral Travel & Projection here.