In general boats work best when used frequently.
When you put your boat away for the Winter, lubricate everything, WD-40 on electrical, mechanical, everything cover up where you can
Keep your battery, (batteries) charged, they will last much longer if they don't ever get too low on juice.
Outboards...lubricate/grease the steering rod connected to the engine...it can rust and become immoveable..bad bad bad!
Always wash your trailer, wheels, undercarrraige with fresh water after use.
Electrical...rule of thumb, it's always a loose ground wire, and check the obvious things first, dirty or corroded connections, loose connections, insulation on wires is corroding
In a repainting job, rule of thumb 0ne-half to 2/3 of the total time is preparation -cleaning, scraping, sanding, dusting, cleaning again.