Well brother, there are a lot of scales and
modes because that There are to much
difficult to know because you can mix the scales too, O.K.
Well after all i think They use the pentatonic a little
and phrigian scales, if you want to do a solo for a song, its easy
because they generally uses three chords and just play around it.
Oh and they start in (E) or in (A). If you have any more questions mail me...