I need to figure out what the best speedpaint brushes areeee

I just use the standard round brush and toggle the opacity and flow. No need to break into fancy brushes just yet.

I just use the default brushes in 99% of cases!

Neat picks, and you've got something going on here! If you keep picking colours with your eyes you'll end up understanding them a little bit better - I often squint a bit to see the right colour. Reading a bit on colour theory would really help you. I think you'd also be helped by putting down more opaque strokes, as well as varying your brush size; putting down a few small details in the right places makes it really come to life I've found!

It's a good start!