Trailered or slipped? Makes a difference. If the boats in the water, the water keeps the boat warm. Air temp freezing and water temp above freezing, it will take a few good nights in the 20's to freeze it. Different story on a trailer.
What year, make, is the motor and drive? Raw water or fresh water cooled?
I use Marine Sta-Bil or CRC PhaseGuard 4 all year long so its in the fuel all the time.
As mentioned, every motor has drains on the engine block, manifolds, oil cooler, power steering cooler. Some have additional ones on the sea water pump and else where. Get a service manual for your motor and get intimate with it. Learn where all the drains are now while its warm out. Sometimes you have to get in some crazy positions and have some great dexterity to get to this stuff. Believe me, I know. When you take the plugs or petcocks out of the block and nothing comes out, don't assume its drained. They clog with rust. I like to use a stiff piece of wire, an awl, even a wire tie can work to poke the holes clean. If we get a cold spell, all you have to do is drain the water til you want to use the boat. Once done for the season, then winterize it.
Oil Change and filter is a must. Oil should be hot. You will probably need a pump to suck it out on most applications. Some have a drain hose that comes through the bilge plug. NOTE: Most oil filters are a real pain to get to if they are not remote mounted, especially Bayliners.
Replace the water seperator now. Dump the old one in a clear jar and see what the fuel looks like
Change the drive oil. If no service records, pull the drive and grease the u-joints if they have a fitting. Check the bellows for cracks. They WILL sink your boat. You'll need a mounting gasget set or o-ring to re-install.
Lubricate all the linkages and grease all the fittings
If carbureated, it can be fogged with spray fogging fluid.
If fuel injected, follow manufacturers recommendations.
Use Corrosion X to protect the exterior of the motor
Store the drive, if kept on the boat in the down position always, even during the season.
Last is removing the batteries and store inside.Check voltage and maintain full charge when needed.
Raw or fresh water cooled will determine how you freeze protect the motor
Capt.Matt