First: Find a private lesson teacher. If your school director cannot recommend someone, then check at local colleges and/or universities. You might need to help pay for your lessons. so be willing to work to help pay for the lessons. (babysit, wash cars, mow lawns). Take ownership for your lessons. Do not miss a scheduled unless it is absolutely necessary. Learn to be reliable now. The best musicians, not only play and perform well, but they can also be counted on.
Along with that-Arrive early to all of your practices and performances. Be the first there! Begin to cultivate this attribute now. I have worked with even college-aged students and professional adults who are NOT on time and reliable! What a pain!
Practice A LOT. When you aren't practicing, someone else is! Don't just play through your songs, starting at the beginning and going to the end. Work each section. Pull a piece apart to learn to play it!
Really spend time to work on technique...yes, I mean scales and exercises. They should take up most of your practice time each day. Learn to see this as being just as fun as playing your songs.
Perform at recitals and competitions, especially the solo competitions which your school district is involved. Use the judges critiques to improve.
Record yourself often and listen to yourself. Become your own best critic!
Attend as many musical events as you can, to hear classical, jazz, musical theater, dance and even pop music. A well-rounded musician is a better musician.
Learn to play the piano! This is a must! If you get a music degree, you must learn some piano and you must pass a piano proficiency exam....even if you are in band and/or orchestra. Also, if you play the piano, even if at beginning-intermediate level, you will more quickly learn your pieces...especially those pieces which have piano accompaniment.
You might consider singing in a choir. You need to see your sax as a "voice" so that it will "talk" when you play. So, your singing will only benefit your instrument playing.
If your school offers it, take a music theory class before college. This will help prepare you for the classes you will take in college.
Listen to A LOT of music! And for sure as many saxophonists as you can!!
If you love music and have amazing skills, that is only part of becoming a professional musician. Know that most musicians are not "famous" although as a musician you will be able to affect many people in a positive way. Do not become a musician so that others can admire you, but so that you can change others lives and help them feel something greater than themselves. Do not count on being famous and making a lot of money. Most musicians do not have a lot of money. I'm a musician, and 2 of my children are musicians/opera singers, and we wouldn't have it any other way. Music is in our soul!! It is our passion! And as for money, we have plenty for our needs.