I'm helping a local death metal band called Asketia record and mix a couple songs. It's a pretty tough gig, since they don't have a lot of recording or mixing equipment, and neither do I. What I do have is some experience and the ability to Google like a goddamn ninja.
We've decided, for the sake of convenience, to go with my electronic drum kit, a staple of everything that comes through the Egg Room here in Rovaniemi, and the band is quite open to recording and mixing techniques. One thing that's pretty common in music production is double- and multi-tracking. It boils down to recording parts (on guitars or vocals, etc.) again and again with slight variations in terms of amps, microphones, guitars, players, whatever you've got. More than that, I've found some info online that suggests that when recording detuned and dropped-tuned (drop-tuned?) guitars, multi-tracking should include root note and double-octave-higher recordings as well to help define and clarify. Speaking from personal experience, if you're not playing riffs on one string (and that string is the low E), that gets nice and complicated very quickly. But these guys, whose every freakin' name starts with J, like they're a freakin' death metal boy band or something, are eager to try anything that gets them some decently produced tracks.