I run stabilizer on three fuel at all times, change oil and lower unit oil. Pull the prop and fear the shaft, grease the zercs on the motor. Then pull the spark plugs throw fogging oil in each cylinder. Mine is in an unheated garage but if it warms up I will use it in the winter. Making sure when I use it I lower the motor all the way down to get water out.
Fresh gas in the spring, start them in the driveway with the muffs, they will smoke a little bit otherwise no issues.