Watch the Play a Melody online guitar lesson by Angus Clark from 50 Radio Rock Licks You MUST Know
The real key to playing melodically is to actually play a melody. Clapton famously stole "Blue Moon" for the solo on "Strange Blue", there's that great live tape where Hendrix breaks into "Strangers in the Night" in the middle of a tune. In this phrase, I'm using "motivic development", where I take a short phrase and then repeat it at different pitch levels as I descend through the scale. Simple, but you've got to play it with some tasty bends and slurs to make music out of it.