Fiberglass is dangerous. You have to have a confined set-up to work with it and spray it in a waterfall booth. This is so that the water catches the fibers in a drain and doesn't release them to the environment You can either paint it or woodgrain it. If you want to paint it, just prime it and paint it like it was a steel door. Woodgraining the door requires gel stain and a graining tool. The Zar brand does a lot of advertising on HGTV (well, at least they did) to claim it has the only system to use to woodgrain a fiberglass or steel entry door, but there are several gel stain systems out there and all of them work.