I`ve been playing for almost 6 years. Two years ago in middle school I played for regionals. So I guess I would be good. But I think that I have not progressed alot in awhile. I used to have good tone. But When I try to play I think I sound horrible (notes aren`t clear, buzzing, out of tune?.) But this summer when I try/tried to play, I put my tbone down in frustration of how bad I was/am. So i need to get my sound/range, and tonguing/articulations and dynamics better, it sounds bad when i do these things. I also need some ways to practice these things that isn`t boring. Also, will getting my braces off improve my sound? Email me or post a messege. please help.

what I really suggest you do is, find a good teacher and i mean good not just any person who has just come out of college. A lot of time we cannot help ourselves progress. we will end up playing mind games telling ourselves we have hit a wall in our playing and just stop playing, something that i recently did. But what i did was go to my teacher, tell him exactly what i wanted out of my playing and he talked me through it. A lot of times to get results its going to be down right boring. so to step up in a level of maturity and sit down and work things out is something you will have to do. So remember the job of playing trombone IS NOT EASY!!! it requires patience and practice.

i hope i helped out a bit, and i hope you find a good teacher. good luck.

here are a couple of things to try.
First get a tuner and play long tones in to the tuner.(booring??) well here is what you are probobly doing, you think your tone is bad because your not in tune. Once you can fine tune your intonation it will help your tone a bunch.
Second take just your mouth piece and buzz.(sounds a little dumb) to make it fun try to do it along with songs on the radio. try to tune your buzz to the root of the cord or to the melody. this will be really funny at first (if you havent done it befor) but keep doing it your "buzzing tone" will get better and so will your tone on the horn but it exponential improvement on the horn.
one more thing if you get bored after a few minits of long tones with the tuner just rock out for like 60 seconds it will help you stay on task. (this is what I have my ADHD student do)
The best idea i think is for you to get lessons. They will help the most.
one more thing are you still playing on a 12c mouthpiece? if you are get a bigger one. 6&1\2is the smallest id go with.
Good luck. If all this doesnt help, try sleeping with the neighbors wife.