In my experience:

Hulls - fair (no bumps or scratches) and then use a good teflon polish. I don't like wet sanding my hulls if they are already fair as that just opens the pores of the gel coat and invites staining. Keep it sealed and clean with a good teflon polish. Wax may be OK but many feel it slows you down a slight amount.

Foils - fair (no bumps or scratches) and then wet sand with 400 grit. A world class sailor/designer told me a 400 grit finish on the foils keeps the water attached better and prevents cavitation so I follow that advice. That same sailor felt you should not put polish or wax on your foils.

Hope this helps.

Bob Hodges