Keeping your hands at your sides during a singing performance is safest. It may not be the most interesting place for them, but you won’t go too wrong by erring on the side of calm and still. If you choose to gesture, make it a complete gesture and make sure that your elbows move out, away from your body.
You may look like you’re flipping burgers if you move just your hands and not your arms. Of course, if you’re using a hand-held microphone, your gestures need to accommodate it.
Another option for your hands is to clasp them in front of you. Clasping your hands at your waistline is cool, but wringing your hands isn’t. Being nervous at a performance is okay, but try not to show it. Don’t let’em see you sweat, as they say. Pretend that performing is the easiest thing in the world.
Your hands can also rest on the piano, if it’s near enough to you and if the lid is closed. If the lid is open on a baby grand or grand piano, don’t put your hand on the lid or inside the lid: It makes your audience nervous to see your hand right where the lid may fall.
You don’t want to put your hands behind you and wiggle them or clasp them right in front of your zipper. Little kids usually put their hands at their zipper when they have to go to the bathroom, so you don’t want your audience to make that assumption. Little kids also put their hands behind them to pick their seat before the show.