So I want to be able to play metal guitar. What are some techniques and shit that are essential to a metal guitarist? And if possible could you provide website links of exercises and stuff? I mostly wanna focus on my picking, I'm a decent alternate picker but I can't pick fast or sweep or do any of that cool stuff. Oh and I'm looking for mostly rhythm type stuff, not lead guitar stuff.
I make up my own exercises, so I would just focus on learning these techniques with scales (for instance, to work on artificial harmonics, try making the harmonics play a specific scale, etc.) and chords for the sweeps. But again, sweeps are probably less important than some of the other stuff. String skipping is probably one of the most crucial, along with alt. picking, just because it frees you up on the fretboard--oh, and don't cheat (no chicken picking).

I was under the impression that you already played (?). In any event, best wishes in your metal studies.