You will be amazed at how much white paint it will take to cover orange if you don't sand it off or use a quality sealer-primer. The best way to sand is to use a board file or for what your doing fart rock. No I"m not kidding fart rock. You'll understand when you use it. Go here and call and order 6-8 blocks. It's cheap too! http://www.fgci.com/.

The beauty of this stuff is it's very aggressive and it conforms to the shape your sanding and is the best thing I've used to fair a surface. Careful using any type of sanding block or power sander. If you work one area here one there and so on you'll wind up with surface that's wavy or not fair.

Then prime w/ high build, sand with a board file,paint and wet sand and buff.

That should keep you busy until the ice melts.