Use a good multi season ablative antifouling paint on the fiberglass. Boats can still have wax on their hulls after several years of use, so a primer for the A-F paint is a good idea. Big chunks of paint fall off on those boats that still had wax on the hull and were not primed.
On a related note. Make sure the steering rod, propshaft and motor's grease fittings are greased well before launch and after pulling the boat. You will hate yourself, if the steering swivel on the motor corrodes, and steering becomes difficult or worse. Spray the powerhead with some anti corrosion stuff, before and after launch, as well.
When the boat is moored, you will want the tilt the outboard motor out of the water if possible. If sterndrive, you will also need some antifouling paint for the outdrive. Aluminum uses special antifouling paint, w/o a copper component.
After pulling the boat, flush the motor with freshwater. My neighbor's deckboat had a stuck thermostat, after not being flushed. Of course, he didn't find that out until after he had the waterpump rebuilt, and it didn't help the overheating issue.