Alesandria,
In order to master any turn in Latin dancing (fast or slow), you must first master the rhythm of the dance. Even though some turns may look extremely fast, keep in mind that they must happen on timing, otherwise your turns will never be consistant. Also, you must "spot" meaning that your head is the last thing to leave and the first thing to come around.(Focus on your partner..eye-level) If it's social dancing, like Salsa, keep your turning arm(s) at a 90 degree angle. Give your partner a little resistance, but avoid being too rigid(that can knock you off balance too). It sometimes helps to bend your knees slightly. Last of all have a smooth relaxed ending...like the turn did nothing to you. Don't look like you're surprized you pulled it off. Smile, breathe and good luck.
Kelly