Begin in front of a mirror on a wooden or other non-carpeted surface. Wear ballet shoes and tight clothing that won't cause you to trip or fall off balance when turning.
Stand in fourth position, left foot in front of the right. Keep your body square to the front, hips and feet turned out and arms loose in front of you.
Practice releves. bring your heels off the floor, coming up to the balls of your feet, while bringing your arms up circled in front of you like you're holding a beach ball. Once you've done a few releves with both feet, releve onto your left foot, still in fourth position. bring your right foot to your left knee as you would when you're turning. Practice this motion, snapping your body up with the moves, until you feel comfortable doing it quickly.
Prepare for the turn, standing again in fourth position, left foot forward. Bring your left arm out to the side, keeping your right arm loose in front of you. Perform a demi plie to set yourself up for the turn.
Bring your left arm into your body to join the right one in a circle. As you do this, snap your body into the position you practiced before--releve onto the left foot and bring your right foot to your left knee. This time, use the momentum of snapping up and bringing your arm in to turn you over your right shoulder. Turn twice before stopping yourself facing forward by stepping your right leg back into fourth position.
Spot as you turn. Focus on one spot in front of you until you can no longer keep your head forward, and then snap your head around to find the spot again as you finish your turn. Spotting takes practice, but it helps to keep you from getting dizzy.
Practice double turns, playing with the amount of plie and momentum to find what works best for you. If you can't make it all the way around twice, work at it until you get it.