The most important thing to becoming a better Musician is to practice. Now I know practicing can get boring, but it shouldn't. If practicing is boring to you, then you need to get some different music. When I practice, I first practice what I have to practice, then I practice some fun stuff.
If you are really into playing music, then you should consider taking private lessons. Private lessons are good because instead of a band environment that has 30+ students, you have a one on one session with a person that is an expert on your instrument.
The most important one of all, Have fun! If you play an instrument and it is no fun, your playing will show it. If you aren't having fun, then make it fun. Come up with interesting and different music.