depending on how big the crack or hole is. if you can do the repair on the inside where neatness might not count. pick up a fiber glass repair kit at local auto /boat store along with a bunch of rubber gloves , fiberglass is at best messy not hard just messy. if yo can reenforce from the inside then you can use a filler on the outside , for the filler check boat shops i know they have filler in differant colors iam not sure about auto places. Then all you need to do is try and match paint
to fiberglass body that is going to tbe the hardest part.
work in small section as the resin sets up pretty fast.