Clothes

It's not necessary to dress in matching costumes (which does work for some bands!), but be sure to project the band's "vibe" in the clothing your wear on stage (or in photos). It's great to be extravagant, which makes you memorable. But it's also OK to be subdued if that's your style. Just make sure you are comfortable in the clothes.

Source : indie-music.com

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

Working the Audience

Make sure you interact with your audience. Make friends with them. Look at them, talk to them between songs, tell jokes, give away drinks or CDs. Don't have those dreaded silent minutes when the audience is waiting while the bassist tunes. Say something witty instead. Be the life of the party. Also work the crowd between sets.

Source : indie-music.com