FishingJoey, Here are some tips for you
1.) Replace the Waterpump (every 3 years)
2.) Lower Unit Service (pressure test) & Fluid Change
3.) Use a Decarb / Tuner for the Carbs
4.) Replace Thermostats
5.) Grease Prop Shaft
6.) Clean the Oil Reservoir (some have filters)
7.) Replace all Engine Filters and Water Separator Filters every 50 hrs epecially if your using fuel with E10!
8.) Replace & Lube the "O Ring" on your Fuel Fill Cap (This is the best place for water intrusion into the fuel....