Penatonic is a decent start, but expand on it, run through it a couple times, palm mute the top notes, even do the zakk wylde lick of

e-15-12-15-12-----15-12-15-12-----
b-------------15-12-----------15-12
g-----------------------------------
d-----------------------------------
a-----------------------------------
E-----------------------------------

The natural or harmonic minor scales will also work, just keep practicing

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