Attitude

The most important thing here is just to HAVE an attitude, some kind of attitude. Nothing is more boring when watching a band than to see musicians standing up there doing... nothing. To continue your image building, your attitude should match the style of your music. (Folk Singers are usually "polite", hard rockers "rowdy", goth bands "serious", etc., but like all rules, this one can be broken.) Do ANYTHING except stand there staring at the floor. Move around, dance, mosh, jump, whatever.

Source : indie-music.com