Newbie question about toan

Hey guys, I've been playing guitar for a while, but a couple weeks ago I decided to buy my first bass on a whim. And a fretless one to boot. I'm having tonnes of fun messing with it! Now my question is how to get a more agressive tone out of it? I'm more of a metal enjoyer and I want to make it sound a bit more gnarly and in your face. I know, using a pick helps, but I'm trying to learn the three-finger method at the moment.

Any help?