edit: https://www.youtube.com/watch?v=x2AwWliVbi0
You’re most likely best sanding it anyway though. I wouldn’t paint anything without sanding prior, as the slightly rougher surface will allow paint to adhere better to it.
How I painted my bike:
sand
degrease
2 coats primer
3-4 coats colour of choice
2-3 coats clear coat.