This question was posed to me by one of my students, a young, up-and-coming player with a great future. So I thought I'd address it and get feedback from all you pros and fans out there.
Of course, the answer is, "It depends." What does it depend on? Among other factors, these can determine how you should dress.
- Size of the group. Are you a soloist? Dress any way you want. Are you in a 75 piece concert orchestra? Dress like everybody else, unless you're the soloist. If you're in a five-piece band, it's worth at least coordinating. And you may think your act is either too small or too unique to work with an image consultant or wardrobe stylist, but looking like a bigger deal than you are might just help you become a bigger deal than you are.
- Style of music. For some reason, I just can't see a death metal band performing in three piece suits and bow ties. Likewise, if you're performing Beethoven sonatas, the shredded jeans and studded mohawk may not add to your overall performance. Do a little research, and develop a good understanding of what some other groups in your genre typically wear, especially those that appeal to you and your natural audience. You can still be unique, but you want your image - your music and your look - to be consistent.
- Type of event. Even if you're a high-energy act, there's a big difference between playing a huge outdoor festival stage and performing at a wedding in a relatively small, elegant setting. It goes without saying, but you should dress to fit your role in the event and to enhance the evening. Much like not wearing contrasting colors, you want your image and look to feel very natural and appropriate for the setting.
- Setting or stage. Similar to the previous point, you should be sensitive to what your audience will perceive from the way you dress. If you're going to be on TV, your dress and coloring will be very different than if you're on a huge stage with thousands of people in the audience. And, again, get some advice and do a little research.
- The band, or your fellow performers. I'm sure you get the point already, but a group - just like an album cover, concert poster, t-shirt or website - needs to look like their image is intentional. That goes for individual performers, too.
Some "standard" ways to dress.
- Concert black. Think symphony. For men, this is usually a basic tuxedo, and for women it's a black concert dress or pantsuit. Some good examples for ladies here.
- "Gig" black. You have a little more flexibility here, but gig black is usually just that - black clothes. For most of the groups I play with, black slacks or jeans with a black button-down shirt or sweater will fit the bill. You can check out a very classy example of this here.
- "Rock star." Actually, it's "insert-the-style-you're-playing" star. It's already been said, but the key here is to coordinate with your mates so that you're all sending the same type of message about who you are, what you play, and the message you want to send.
Finally, let me leave you with another little bit of wisdom that has helped me since my high school days: "Your audience will hear you with their eyes before they hear you with their ears."