Re: painting the front door red
If it's a fiberglass door with wood grain and texture, then you'll wash it down with a mild TSP solution, rinse, allow it to fully dry. It's always best to prime first, so a coat of Zinnser Bullseye 1 2 3 (blue label ), then two coats of a good quality paint, such as Kelly Moore, Sherwin Williams, or other major brand. Stay away from Behr products.
If the door has a metal frame with a rough textured panel in it such as you'd find in a typical commercial restroom, that is an FRP panel and you won't likely get paint to stick to it very well. You can try, but don't expect much. Like above, you'll wash it down, rinse, and let it dry. Go to a paint dealer (as mentioned above ) and ask for paint and primer specifically suited for painting FRP products and apply per the label directions.
TSP = Tri Sodium Phosphate. You find it in any paint or cleaning supply department.
FRP = Fiberglass Resin Panel. Trailers, mobile homes, and manufactured homes are notorious for making doors out of this stuff. In the real world about the only place you'll find it is a public restroom wall covering.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!