Pick a simple trick suited to your skill level, ideally one requiring few or ordinary props, and learn the method thoroughly before ever performing it in front of anyone. Practice in front of a mirror or record yourself to check that your movements look natural rather than suspicious, since misdirection depends on your body language seeming completely relaxed. Rehearse a confident patter (the words you say while performing) that draws attention where you want it and covers any secret moves, since audiences follow what you talk about as much as what they see. Never repeat the exact same trick for the same audience right away, since they'll know what to look for the second time. Above all, never reveal how a trick works — the mystery is the whole point, and magicians who explain their secrets lose the audience's trust.