Personally I use pink insulation foam from home depot for my molds. I cut the molds using a hot wire cutter (re: a small car battery charger with a piece of safety wire connected to the leads and it set to the lowest amperage) and then bondo the hell out of the mold. After its fine sanded its then highly waxed, then coated again with a special release agent. At this point the glass is layed up onto the mold and the resin is applied. Personally I recomend West System Epoxy, not that bondo crap epoxy. The west system is very predictable and easy to work with. Personably I vacuum bag at this point but thats kinda advanced. I personally recomend heading over to
Aircraft Spruce and checking out there composites section. I buy most of my stuff from there, and there catalog is full of helpful hints.