Beginners almost always float face down.

After one is comfortable that way, it's time to float face up.
 
Either way you must always be prepared to crash. Even veteran floaters crash. I've taken to wearing a bicycle helmet and elbow pads.

Levitation is, of course, always performed in a reclined position (although there are tales of a floater from, of all places, Detroit who could hover totally upright.)

With experience you can roll over in the air. Doing it is kind of like launching in the midst of your float.