I find that a good way to improve is watch people who are better than you. What are they doing that makes what you do sound better (vibrato, little bends can be simple stuff) often though, it's the hours and hours and hours they've put in practicing that I haven't. I have a good friend, Nate Graham, he told me about a book called 10,000 hours (i think...) anyways the premise being, people at the top of their trade, sports, music, computer programmers, whatever have put in 10,000 hours of practice. That's a lot of stinking time. but to be honest, as I think about how i spend my "hours" i waste a LOT of time watching tv or on facebook, if i put that time in to music, i couldn't even imagine.
Anyways, I've played guitar probably for 4 hours today and I'll watch youtube videos of joe pass or brubeck or slash or rehinadrt or john mayer or whoever and i find myself feeling very defeated, but then i think, "they didn't get to be talented by feeling defeated" so i thought i'd throw some encouragement out to people who may need it. Don't let someone better than you defeat you let them challenge you. And it's time to rise to the challenge
maybe motivational speaking is in my future...