Maintain eye contact with your audience. Use the secret of eyeing two or three people in the crowd and play your instrument or sing directly to them. This gives the audience a collective feeling that you're connecting with them.
Use larger gestures than you would if just giving a speech. Singers need to show the passions of the songs they're singing by gesticulating in ways that convey the meaning of the song. Use one arm for the gesticulations if you can while holding the mic so the gestures won't look overdone, unless you're singing something overly histrionic or using a headset microphone.
Project into the audience the musical instrument you're playing if you're performing with an instrument that allows moving around the stage. Aim the instrument in a way that appears to be playing toward the audience, for instance a horn's open end tilted slightly toward the balcony or a guitar always facing forward. Gesticulations with one arm can be effective if you have a free arm while playing a long, final note.
Dress in clothes that befit the type of concert you're doing. You can't work a stage or get an audience to take you seriously unless you're wearing the appropriate clothing for the genre. A rock concert generally means wearing jeans or leather pants and T-shirt. A jazz concert usually means casual dress clothes. A classical concert usually means a tuxedo or suit. Experiment, nevertheless, for the sake of creativity, but don't take too many risks.
Move around the stage while you perform, which includes stage left and right, center stage or a walkway that allows more audience interaction. Do this in combination throughout a concert so every section of the audience will know you care about them.
Hold the microphone in ways that convey emotion, particularly closer to your mouth when belting a final note. Avoid holding it too close to your mouth consistently or it could cause distortion, even though some rock concerts intentionally do it this way. Show your mouth while you sing so people can see that you're truly singing and not lip-synching. Create your own way of holding a microphone to give you a distinguishing quality from others.