Preparing car for paint job

Hey guys ive decide to do my own prep work and then let a professional do the paint job. I was wondering what to do to prepare the car? Any special products i should use? Also i wanted to know what grit sand paper i should use to sand the car down. I was wondering if it was ok to sand it down to bear metal until it is prepped and painted by the bodyshop?

Car has to be sanded with 400-500 wet or 320 dry for most basecoat clearcoats. If using acrylic enamel you can sand with a courser grit. Thats final sand. Of course any bodywork areas will need a courser grit to do anything and will need primer and sanding working down to the final grit listed above. Don't leave any bare metal. You are going to want to get some epoxy primer on bare metal as soon as possible. Then later on the epoxy primer can be scuffed and if needed urethane primer sprayed on and body filler can be used over the epoxy primer.

After sanding the car down, what is the best kind of spray can primer to use, before i take it to the body shop to get sprayed, and possibly reprimered if necessary.

alot of shops wont paint the car unless you use primer they use at the shop