It is easy to assume that your winterized boat was put away in the fall and will be ready to throw in the water when you are ready to use it now. Not always really the case. A few basic checks can make the early first trips smooth.
Boat batteries that were charged and not tended to once the boat got put away, will need to be charged and checked. Most boat batteries will have a 3-5 year life span. Used heavy, many marine batteries will only give you 2-3 seasons. Make sure connections are also cleaned.
Clean out compartments and repack equipment into your boat. You will know where everything is. Hopefully you changed lower unit oil in the fall, changed oil in 4-strokes, added stabile to gas when it was put away. If not, do all those preps now. Start the motor and run on muffs before launching it on the lake and not being able to get it to start our run. These problems are much easier to resolve at home. If a qualified marine expert winterized for you, your money was well spent. Add fresh gas. Boat motors run much better on fresh gas.
Boat trailer tires will lose air sitting in storage buildings. Make sure bearings are in good shape and tires are properly inflated. Wiring can get goofy after months of not being used. Mice, rust, corrosion are all common gremlin names. Hook-up and check the trailer lights before heading down the road. Grounding issues can make wiring act goofy. Buff the rusted ball hitch with a wire brush or drill with a wire brush to ensure a good ground. Shoot a silicone spray into wire connections and plug and unplug them several times to make sure you have good contact.
A great trick to cleaning the exterior of the boat and motor is to use white vinegar. There are many products sold to remove mineral deposits. White vinegar is cheaper and works as good, if not better, than other products on the market. After washing with soap and water you will notice water spots on the boat and motor. Buff with a rag soaked with white vinegar. It will take some elbow grease, but it will start to feel smooth and the grittiness off the minerals will dissolve. Have a clean, safe, and trouble free boating season.