Watch the Electric Groove Solo online guitar lesson by Jeff Scheetz from Blues-Rock: Secret Sauce
In this solo, we're looking at several ways to make your playing sound a bit "outside", or in other words, sound like you are using notes that are not in the normal scale or key you are in.
Players like Jimmy Herring use this technique to spice up their playing - it keeps you from sounding like you're stuck in the pentatonic rut repeating the same licks all the time.
Practice the riffs and work on expanding your ear by listening to "out" players to get yourself more familiar with the different sounds. Start small, don't try to go "out" on every phrase - just go a little out there for a monet or two and then come back home again!