When the boating season ends, idealy you should remove your outboard motor from the boat’s transom, clean and lubricate it, and mount it on a storage stand.
However, many owners just tow the boat home and leave the motor in place, perhaps throwing a tarpaulin over it. After several years of this kind of neglect, a motor will need expensive professional service.
There is a compromise approach, in which you service the motor on the boat to prepare it for the off-season. When the boat is home, clean the cooling system, using a garden hose connected to an adapter on the motor’s water intakes. Remove the propeller, wood block (to restrain propeller), lock washer (bend tabs down to release nut; up to hold)then run the engine at idle to circulate water through the passages until only clean, fresh water comes out of the exhaust (dip a forger in the water and, without swallowing, taste it to be sure it is not salty). Even if you operate only in fresh water, flush the cooling system to remove silt and dirt. In either case, also hose off the motor housing.