Next year will be my senior year. I will be first chair in Jazz, Marching, and symphonic bands. Does anyone have any tips, as I`ve never done this leadership thing before.

Never flinch at a solo assignment. Know your music better than the rest of the section, and always be ready and willing to share your knowledge and techinique with the rest of your section, but never be arrogant. Know that you are the master of your instrument (it cannot play itself). Communicate with the other section members to learn if anyone is having difficulty with a particular piece of music. When that happens (and it will) try having "section meetings" without the rest of the band to work out the rough spots. Establish a warmup routine for the whole section to go through together before each rehearsal. It never hurts to arrive for rehearsal or a performance 5-10 minutes before the appointed time. You have obviously earned the status you will hold your senior year. Make the most you can of every minute of it. Good luck!