Here's my winter storage checklist I follow, which I found and tweaked slightly. The checklist I follow is pretty much identical to
this article on Wheels.ca.
Winter Storage Procedure
1. Change oil and filter. If you are nearing your coolant and brake fluid flush intervals, do them now as well to have fresh fluids in.
2. Fill the tank with fresh fuel from a top quality station using high octane (no alcohol if you can help it).
3. Go for that last short brisk drive to burn off any moisture anywhere.
4. Use a gas preservative/stabilizer such as STA-BIL. After you put the fuel stabilizer into the tank, let it idle for 5 mins to distribute it throughout the entire fuel system.
5. Wash and wax your car right before storing it. Make sure it is fully dry in all the crevices.
6. Clean your interior and vacuum it out, use leather cleaner/conditioner and vinyl cleaner/conditioner as required. Treat all rubber with a good rubber cleaner/conditioner. Do NOT use water on the carpets/seats right before storage, or you risk mold and mildew developing.
7. Put an open box of baking soda inside the car on the passenger side floor or other suitable place. This absorbs excess moisture in the air. A large bag of desiccant gel works as well.
8. Over-inflate your tires. Over-inflating does NOT mean going over the max psi printed on the sidewall! Never do that, but you can come close. I use 45psi. This reduces flat spots on the tires. They will still happen, but will be smaller and you will recover from them faster in the spring this way.
9. To stop moisture from getting under the car put a couple layers of plastic sheeting under the entire car and several feet either side/ends. If you store it in a heated dry facility, this may not be necessary.
10. Park the car with some hard cardboard or plywood under the tires to put a tiny bit of space between the tires and cold concrete. Do not store the car on jack stands with wheels hanging! You risk damage to your suspension components if you do.
11. Make sure the handbrake is disengaged to prevent pads from sticking to rotors over the storage period. Put blocks under tires to prevent the car from rolling. You can leave it in gear. It should be parked on a level surface anyway.
12. Put the system on max a/c for a couple of seconds before shutting off to close the outside vent. If the garage is heated, crack the windows open a little bit to allow air circulation.
13. Put steel wool in the tailpipes and air intake duct at the front to prevent any critters from treating your car as a luxury winter accommodation. This is especially important in unattended facilities.
14. Connect a quality battery tender to the connections under the hood (not to the battery directly). It is not necessary to take the battery out of the car nor disconnect it. If you do, take the usual steps to be ready once you reconnect it, like having a radio code ready.
15. Leave yourself a sticky note on the dash or steering wheel to remind yourself to undo some of your steps above in the spring like: disconnect battery tender, take out the steel wool from the pipes/intake duct, remove baking soda, adjust tire pressure, remove wheel blocks.
16. Cover the car with a high-quality car cover made for your car. Low quality covers will scratch you paint, trap dirt and moisture underneath and are many times worse than not using one at all.
17. Kiss your ride goodnight for a few months.
IMPORTANT: Do not start your car while it is stored unless you plan to actually go for an extended drive and get it fully warmed up and burn off moisture that will happen with a cold engine start-up. If you do, repeat the procedure above. You may be tempted to do so on a sunny dry day in winter, but keep in mind all the dust and salt on the road that you will collect and bring it back with you from that ride. Simply, don't do it.
Hope this helps.