Service, Hmmmmm---------
If your brake or clutch fluid are not clear and/or are darker than pee-pee, you need to bleed!
If you may not ride for 30+ days, plan on a dose of fuel extender blended and run a little while before you pickle the bike. Modern fuels may spooge your fuel system in about 72 days. You will be cleaning carbs and tank.
You should also take a phillips and a rag and drain the float bowls after she cools down.
If you "miss your Bud" and have to go out to the shed to look at it, Don't start it unless you are ready to run it till it's hot, heat cycled, and drained again after the run.
If there's nothing wrong with your bike, the battery will start it after sitting for months after you park it. Yea, right.
Unhook the negative (black or - ) battery lead. Heck! take the battery out and keep it in your nice warm house (out of reach from children and pets, away from all flames or extreme heat sources, no liability implied, see future disclaimer) batteries of the lead acid type don't like the cold. Cap charge battery day before re-installing.
Either have a back up bike, or do your improvements, repairs, cleaning, with great dispatch! It is a terrible thing to have a beautiful riding day(s) and a bike in pieces.
Modern tires are REALLY well made, They don't need much more than air pressure checks and replacement when done. You can levitate your bike if it makes you feel better.
If you have a British bike, You must replace all the peat moss in the electrical system to confound the gremlins.
The best thing you can do is get some cold weather gear and don't stop riding. Do practice on the ice in an open place, as you may do less damage that way. Yea, i know thats stupid, But, The most beautiful ride I was ever on was in the snow in Suffolk England on an RD350.
When you get it back out that nice spring day and are ready to start up, leave the throttle kill switch off while you turn the engine over for about 20 seconds to get the oil around the motor, then start it.
Be careful! God Bless!