Develop your ear and your sense of melody, phrasing and time.
I did this by figuring out songs I wanted to play, by EAR. No tab and no how-to-play-x lessons from youtube. You have to develop your ear for music.
That said, there are some lick lesson type things that can help with your vocabulary.
- Jeff McErlain has several 50 licks type lessons on Truefire that I like. He covers stuff others don't, like licks/riffs in the style of David Grissom. Grissom is hard for me to pick out by ear so I found that valuable.
- Greg Koch's lessons are thorough, accurate and useful. His Country Guitar and Blues Guitar method books would be good for beginner to intermediate guitar players IMHO.
- If you like heavier rock or metal, Curt Mitchell does a great job of explaining stuff so his song lessons end up teaching you things beyond the song itself.
Also, make sure you learn at least a few things from outside your favored style. It helps add spice and little touches that otherwise would not show up in your playing. I started as a blues and blues rock (Free, Bad Co, Led Zeppelin, Stones, Joe Walsh) guy but ended up learning some country stuff (Roy Nichols, Johnny Cash, Early Eagles) that really changed the way I approached the instrument.
Learning all the fills and solos to the Amazing Rhythm Aces - Third Rate Romance was a big turning point for my solo and rhythm work.