If you not going to use bike in winter, I agree with G0MYW, take the battery off and take inside. Even if in warm environment will lose charge, I put mine on a Optimate in winter. All my bikes have lived on Optimates over the years in winter. Cold knocks **** off batteries.
As for protecting the bike, if in cold garage, my personal view is spray it all over with ACF50, (avoiding the brake discs) Because even in winter you can get condensation, water on the bike. Water and metal = rusting. With the very cold then warming up creates the condensation very quickly.
A coating of ACF50 or Muc-Off corrosion defence, will protect. Even a spray with WD40 or GT85 is better than nothing.
Make sure full of fuel, no room for air space to condense inside the tank.
As for starting your bike during winter, there are 2 schools of thought. 1 says start to warm everything up to dispel condensation, the other is leave alone . Another opposite views are about covering the bike over, 1 suggests you do, another says no prevents air circulation. Up to you, I personally before parking up for winter, give the bike a good wash,clean, dry and polish. Take for a little ride to warm everything up. When cooled down I go daft with ACF50, plug in Optimate and kiss her goodnight til spring arrives.
Or you could go for a Vac-Bag, I have never used 1, but a mate swears by them.