Watch the Changes: Rhythm online guitar lesson by Jeff McErlain from Blues-Rock Evolution
I always try to play with musicians I can learn something from. On my first tour, the other members of the band were seven to ten years older than me, and great players. I wanted to earn their respect and as a result I got much better in a very short period of time.
Now, in my own trio, I try to find players who will push me and the music to the next level. If you can, play with musicians who are better than you.