Sanding out orange peel in clear what grit to use first?

1500 wet, then 2000 wet, then bring the gloss back with a buffer. Using the buffer is also progressive. You will need the appropriate pads and compounds (this depends on which system you go with).

You could also go 1500 > 2000 > 3000 then polish. (less buffing time but more wet sanding time).