For just a light frost, a blanket wrapped around the lower end will probably be adequate to keep any water that might be in the lower unit from freezing until you get to replacing the gear lube. However, I would be inclined to do it now instead, if you really are only going to use it a time or two more. Tilt the motor down. Outboards are designed to self drain, so to remove all water from the cooling system, merely store the motor tilted down. Fill your tank with stable before your last trip, so it will run through the motor before you store for good.
When you decide you have had enough boating fun, then change your lube, fog the motor, and be sure to put the batteries in a warmer environment, on a trickle charge.
Not much else.
I use mine all winter, so all I do is replace gear lube before the first freeze, and as long as no water has entered, I can usually count on it to not leak through the rest of the winter. If anything happens to lead me to believe it might start leaking, I'll change it on through the winter. Then, I store with the motor tilted down.