I know I say this on all of the tunes, but this one is tricky with some quick fills that jump from the fifth fret up the octave on the nineteenth then back down. My suggestion is to slow everything down first, leaving out the fills, first learning the riff and groove to get it solid. If you're having trouble getting the fills, simplify them; they're all out of A minor pentatonic.
Also, play it like you mean it! Really digging into the notes makes a bit difference in not only how the tune sounds but how it feels. You can't sound like Johnny Winter and play tentatively. On this particular tune it's important to dig in, but even on mellow tunes it's a good rule to never play (and live) tentatively. Always dig in, even if you are playing softly on a ballad, be present and play that guitar!