So you want to make some music: But with all those instruments to choose from, how do you know which one to pick?
First, think about your musical interests: Why do you want to play? If you want to be in marching band, it's clear that you shouldn't pick the cello. If you and four friends want to become the next Maroon 5, you'll get closer to that goal by learning guitar as opposed to clarinet.
Next, find a way, either by going to your school's music teacher or to a local music shop or by checking out CDs from your local library, to listen to every instrument you have choice of playing. Are there any that you like the sound of more than the others?
Consider the size of each instrument, as well as physical limitations to playing each. A smaller person may not be comfortable carrying a tuba around, just like a football player may have hands too big to play the piccolo. If you take the bus to school, or even if you have a long walk, a trombone or bassoon case might be cumbersome. Think about how the instrument feels to play. Are your hands big enough to reach all the keys (bassoonists especially benefit from having long, thin fingers)? Are you comfortable holding the instrument, both sitting and standing? Do you prefer an instrument that uses a neck strap (like the saxophones and sometimes bass clarinet) or one that doesn't?
Find out what is involved in taking care of the instrument you are thinking about selecting. Some instruments have a lot of keys that need to be cleaned; others have parts that require oil. Still others have parts that need to be replaced — woodwind instruments require new reeds (relatively inexpensive) on a frequent basis, while stringed instruments occasionally require new strings and re-hairing of the bows. Find out what your instrument needs to stay in good working condition.
Finally, weigh your options carefully. As a young adult, playing an instrument might be one of the first long-term commitments you make. Purchasing or renting an instrument isn't cheap. Many music programs (even music shops) require you to sign a contract for up to a year where you'll pay rent on the instrument even if you never pick it up. Concert and marching bands rely on consistent membership, so you might not be allowed to drop a band class until the end of the year. Performance attendance is mandatory or your grade will suffer. Do the research up front and pick an instrument you will enjoy playing.