Decide what type of music you want the teen music group to play. This influences what members you need. For example, if you're starting a singing group, you need several great singers. If you're starting a punk band, you need a singer, guitarist, bassist and drummer.
Recruit members for the teen music group. It's often best to start with your friends or acquaintances, but you can also advertise. Be clear about what you're looking for. For example: "Seeking 13- to 17-year-olds interested in starting a pop/punk band. Need guitarist and bassist."
Find a practice space. You can rent a space or practice at the home of a member. You need a space where your teen music group can comfortably practice without getting the cops called on you for making too much noise. If you're practicing at a home, talk with the neighbors to make sure it's OK.
Acquire music to play. This means writing your own music, hiring a songwriter to write music for your group or playing covers, which are songs originally done by other musicians and bands. Choose music that fits the style you want and that you're able to play. While it's good to push yourself, if you pick music that requires a technical skill none of you is close to possessing, you'll just end up frustrated and never get the song down.
Practice regularly. You don't have to practice five days a week, but a regular, consistent schedule helps you get better.
Decide on an image for your group. This usually fits with the style of music you play. Pop/punk bands often wear punk and skater clothes, while boy bands wear some of the current mainstream fashions.
Choose a group name that fits your style and image. Metal bands often have gory or intense names, while teen pop groups have names with "boy" and "girl" in the title, like Backstreet Boys and Spice Girls. For ideas, look at other groups that play your kind of music.
Record a demo, which is a sample of the music you play. This is also how you get shows and gain attention for your band, other than through performances.
Book shows. Many bands play at bars or other adult venues, so being a teenager makes it harder to book shows. However, there are still many options for performing. Look for teen clubs in your area, as well as parties, coffeehouses and schools that host bands. Many high schools throw benefit concerts or battle of the bands, and these are great opportunities for teen music groups to get exposure.