If you know that you are NOT going to use it , bring it inside (warm)and place the battery tender on it, IF you might use it , do what Wolf said, leave it hooked up and trickled.
Be careful when looking for that ol trickle charger, some will charge and boil the acid right out, some have the little computer chips in them and cycle and maintain the voltage. Get one that will cycle on and off according to charge.
One cooked battery is enough to wish you had bought the better maintainer !
btdt !