just always keep in mind that sweeping is concitered by many guitarists to be one of, if not the, hardest techniques. i know this site has some lessons on it.

but what i would do is work on some of your other metal techniques first- alt. picking comes to mind. some of those can help you before jumping into sweeps.

sweeping takes awile man. ive been playing like 4 years now and i cant do them up to speed.