Practice practice practice !! I switched up to a 2mm Big Stubby, others go to a lighter pick but I personally like the thicker picks...for some reason lets me go a touch faster, faster response or something. Uhh listen to a lot of Slayer and just get your hand going....there are other 'exercises' heh but yeah not allowed to say muahahaha. But yeah try different pick thicknesses oh and try your damndest to keep the pick flat. A lot of people have problems with turning the pick at a angle, yes this let's them go faster but it doesn't sound as good and if you practice for a bit flat picking you'll just as fast and have that nice chunk instead of a scrapping sound. Oh and get a guitar made for trem picking, I have a V plus a Strat, naturally the V plays a bit faster for me, might just be all in my mind but doesn't seem that way =P