I've played guitar for about 3 years now, played rhythm for a pop punk (rise against esque) band for about a year, so I've got decent Rhythm.
I play for a heavy metal band now, older style of metal, and I've learned a lot of the old style of metal, I.e. Megadeth, Slayer, In Flames, Trivium, Testament, OverKill, and such, while I can't play solo's all that well, I can run pretty decent heavy riffs.
I've also dabbled in acoustic music but that doesn't really have much effect here.
anyways, main line of this story is I picked up a dirt cheap bass guitar because our band needed a bassist, and our other guitarists have it down anyways, so after playing for about a week I managed to learn (not completely memorize) Souls of Black - Testament, and Hysteria - Muse, both using strictly fingering. So I feel I have the riffs down alright, where I struggle is pulling off primus style playing, the slapping, popping, left hand slap, that sort of style, so does anyone know any good techniques or places I can learn that sort of stuff? Does that even have a place in Metal?
Also, what are good scales to learn?

Oh, and I know virtually nothing about theory... Should I work on that?
You know that shiver you get when you hear an amazing guitar riff? That's what i want my music to do.
Don't limit yourself.

Just because you like Metal now, it doesn't mean you always will. So, don't limit your skill pool! You wanna slap? Learn it. It doesn't matter if you can use it in 'metal' or not.

If i could re-do my bass history, it would be to expand on everything when i first started. I played punkish stuff ONLY (ex: Orchid/Pg99/Majority Rule/Botch/Reversal of Man/Converge) for YEARS... sure... i got to tour the country for a few years... but after the band split i was left with skills to satisfy only ONE type of music, even though i had been playing bass for about 10 years.

While i still love that stuff, it's MUCH harder to find people who even KNOW those bands... let alone desire to play in a band like that.

So, at the not-so-young-not-so-old age of 25, i decided to finally expand my horizons. I'm now 28... i can play things from Motown, to Classic Rock to Funk. I can read music, and i'm not playing bass in the pit for a musical. I only wish i had gotten into this stuff sooner!!

"Punk Rock should mean freedom, liking and accepting anything that you like, as sloppy as you want, as long as it's good and has passion."