I have fiberglass exterior doors on my home-how can I prep for paint?

Remove the existing stain with Citristrip a non toxic remover,prep with a exterior primer,allow to dry and paint with a exterior paint for fiberglass

Strip the gel stain off. Use marine stripper that's use for fiberglass boats. It's powerful so wear heavy rubber gloves. Once cleaned, prime with a primer for plastic. Then paint with a good acrylic.

Note: if you're using a dark color on door in a sunny location, the paint will fade. Recommend in this case using oil paint.

Marilyn - Sorry this is such a long answer. It never pays to hurry this sort of project because if it goes bad, you have to redo all of your prep and start over. Preparation is the most time consuming part and is same as for most door painting projects. You will need to sand the door carefully with a very fine grade of sand paper and clean it well so that it is dust free. Tape off any window areas and you can either remove the handles (I do) or tape them off. I made sure everything was bone dry, [by waiting to the next day] before. I don't know if you want to spray paint it, but you can! Rustoleum 2x is a great paint for that approach. The link below is an interesting discussion of guys painting many things (including fiberglass). Read their comments before you start and it may help you have success on your first attempt. http://www.rocketryforum.com/showthread.php?6300-Rust-oleum-Painter-s-Touch-Ultra-Cover-2X In the alternative, I have had great success with painting my front exterior door with the Home Depot Behr Premium Plus Ultra Stain Blocking Paint and Primer in One, which had to be brushed on. You will only need one quart. Yes, it was expensive (to me). I discovered it was worth every penny! It was recommended to me by a man who used it on his shutters. He reported they have had no fading or cracking in the Texas Sun in seven years. I was very surprised at how well this paint laid down, no brush strokes showed (I admit to being an amateur), and although I was laying a very dark color over white, two coats were all I needed. This paint comes in a lot of great colors. You will feel very good when that door is done! It makes such a difference in the appearance of the house. Best wishes.