I fish all winter long. Here is my routine: 1. load the boat and pull it out of the way, 2. trim the motor down and wait for all of the water to drain while I pack up everything else, 3. tilt the motor up, wait a few seconds and trim it back down so it can drain some more, 4. tilt it up again, wait a few seconds and trim it back down, 5. tilt it up, put on the transom saver and go home.
That may sound like overkill but with the price of a new lower unit I can take an extra 2-3 minutes to keep mine from freezing.