Throw some additive in the tank if you have summer fuel (or it will not start until the spring, no matter what you want), close the windows, and put it on a battery maintainer (you can disconnect the batteries too, but there is no need). If the garage might have rodents, put some bait out. I have found leaving the hood open discourages them from trying to nest in the engine bay as well (but then your engine gets dusty, so choose wisely!).
5 months of sitting won't hurt anything. The only potential issues are dead batteries, rodents, dust, and gelled fuel (if you need to start it when cold). Not hard to take care of :thumb:
To un-winterize it, I recommend changing the motor oil after the first or 2nd heat cycle on the motor. This is not strictly necessary, but it can get rid of any remaining moisture/whatever that doesn't boil out on the first drive. That, and give it a bath, I am always amazed how much dust accumulates in 5 months!