My daughter (4) helped me paint this. First time I've done a skateboard, I've been meaning to for ages because this board was crying out for more colour.
Process was simple:
scrape the stickers off (this was probably the hardest part)
lightly sand to get a key on the existing paint and smooth any gouges in the board.
2 coats of water based primer
poster paints and sharpies for colour and design
several coats clear polyurethane spray varnish
allow it to dry fully, lightly sand and buff to get a smooth-ish finish
I'm happy with how it turned out, although I'll give a bit more thought to the graphic next time. I didn't have much in mind so just went with my daughter's rainbow suggestion