Watch the Me Solo online guitar lesson by Jeff Scheetz from Blues-Rock: Secret Sauce
Melody. You've heard it said that "melody is everything". Well, certainly no argument there. So being able to come up with interesting and memorable melodies is not only crucial when you're trying to write a pop song, but this is also especially true when you're laying down a solo.
Some guys seem to always land on the right note. Warren Haynes from Gov't Mule is one of those cats. He seems to always pick the best note to land on, creating incredible melodic phrases.
Work on "listening" to develop tasty, melodic solos. It's not about how many notes you're playing - it's about playing the right notes at the right time. Your ears will guide you if you're paying attention.