In addition to what spddracer said, I would also remove the interior. The reason is that sometimes even if the car is masked properly from the outside, paint overspray will make its way to the interior, and it is such a PITA to get it off. Also your fenders have to be aligned before painting the car. I would recommend having the body shop align it for you just to make sure it looks perfect. If you're set about doing this, then make sure it is done right. It is not worth taking any shortcuts because if it looks tacky, it will ruin your car's appearance and resale value.
