Purchased 2 nice (expensive) fiberglass double-doors a while back. I an a pretty experienced carpenter/woodworker, but not so with fiberglass. I was told I needed to use MinWax Gel Stain w/sponge brush. Project would be difficult & I would only get one shot to do it correctly. The old lady I've lived with for 41 years is ENCOURAGING me to get on with it.:-] Does anyone have any experience with this material, any suggestions or resources to check before I plunge into the project?
Any advise would be warmly received!

Yes you do need to use a gel type stain as regular stains will not work. These doors are a bit difficult to do but they do turn out nice. You can use a natural bristle brush to apply the stain which I think will do better than a foam one. I would start with doing the panels first and then finish up with the center sections and then the outside stiles. I also would have two brushes, one to apply the stain and the other to even out the stain once it is on the door. Once you have stained the door allow it to dry until the next day (24 hours) and then apply at least two prefrably three coats of a marine spar varnish (oil based) to get a good protective coating over the stain. If this door gets alot of exposure to the elements you may have to apply more varnish every eighteen months or so.