Unfortunately, practicing is underrated. Anything worth doing requires a great deal of practice, but I see people all the time that just don't get it. They think people are just "talented" or that skill is basically equivalent to magic. Those people are wrong.
Being a skilled musician is about dedication and regular, regulated practice. I have put together some of my favorite practice tips:
1. Actually practice. Like, get out your instrument and play it. Schedule time, force yourself, and do it at least semi-regularly. Don't pretend, don't make excuses, practice or resign yourself to being lousy.
2. Log your time. It seems stupid, but if you'll log when, how long, and what you practice you can better evaluate if you're being effective.
3. Only play as fast as you can play accurately. You know what I mean- you have a nifty solo you're working on, and you want to play it quickly, so you totally butcher the whole thing. Well, that's a waste of practice time. Practicing something fast and wrong ten times is going to hurt more than help. Just play it slow and correctly, then add speed. It's better. Really.
4. Don't forget fundamentals. Scales, arpeggios, and technical etudes have been around for centuries because of one thing- they work. Fundamentals are well, fundamental and should be a significant part of your practice routine if you want to be more awesome.
5. Incorporate play. Make sure you play some music you're excited about and make sure you spend some time just "playing" your instrument. Improvise, play along with the radio, or learn obscure techniques for instrument or special sound effects. Get your funk on, or something like that.
6. Listen to music. I think this is self-explanatory, but it's amazing how many people don't listen to someone who plays their instrument. It will inspire you and change the way you play forever, in a good way. Unless you listen so someone who sucks, so don't do that.
7. Goals! Don't just practice the same things, challenge yourself with new materials and things that will stretch your skills.
8. Practice buddies. Get a practice buddy and play some duets. Challenge each other to practice more and use each other's ears to craft better sound. There is a danger that one of you might quit and ruin the momentum so make sure you are a strong practicer by yourself as well.
9. Find a good method book. A good book will have an excellent progression of skills. It will grow you gradually and fill in any gaps you may have in your learning while also establishing a future path. Things like the Arban Book for Brass, the Deville Book for Saxophone, or the Klose Book for Clarinet. (Those last two are public domain and free, Click the link)
10. Get nerdy. Dive in and learn all the weird things about your instrument. History, famous players, and instructions techniques. These things will enhance your practice and inspire you.
Most importantly, don't give up, and good luck.