Here are some tips for an easier start after winter storage. You can of course just park the car for winter, but it's usually smart to take care of a few things especially in colder regions to ensure minimal problems when your car is getting back on the road.
Fill up the tank.A full tank wont get condensed moisture. Water it's self is not dangerous, all though on older cars it can corrode a metal tank. Water can however block a fuel filter or injector completely or partially causing all kinds of running issues. Modern gasolines usually contain 5 to 10 percent ethanol which can absorb it's weight worth of water. In other words 60 liters of 5% ethanol fuel can absorb ~3 liters of water.
Use a good fuel like V-power or similar. Premium fuels stay usable for a longer period of time. Products like the Red Line SI-1 or RL-2 can also be used as additives to prolong the "shelflife" of fuel. Old fuels will cause running issues and cause higher emissions which usually are a cause of a failed MOT inspection.
Tire pressures should be on par or a little higher than rated. A low pressure tire can develop a bump in it, and it takes a while for it to straighten up. Proper pressures wont allow the tire to flatten too much.
Completely charge and remove the battery. A dead battery is way too common. Be on the safe side and take it inside and charge it a few times in a well ventilated space during winter. If your car has start-stop or other similar functions, check the manual or dealer for instructions. On regular cars the battery is safe to remove.
Open the windows a little bit. You want a fresh car, not a damp moist smell, so taking care of ventilation is important. As long as your car is not outside, windows can be left a little open to allow ventilation. Emphasis on the word little, as you dont want to find any critters in your car in the spring.
Moisture absorbers are also a good choice when storing outside, or if you want to be absolutely sure your interior stays dry & fresh.
Locks and hinges always benefit from some WD40, but especially after not using locks for a long time, they can seize if not properly lubricated.
Change the oil before storing. Oil is a lubricant, but also a slovent/washing fluid which absorbs all kinds of chemicals forming in combustion. These chemicals can at worst be corrosive, so you might want to consider changing oil before storage to keep the engine pristine and avoid any buildup of clog in the oilpan.
Put a plastic underneath the car if you store it on other than concrete or tarmac surfaces. Dirt and especially grass give up a lot of moisture, and everyone knows damp conditions and suspension don't come along well. A simple piece of plastic blocks moisture coming from the ground and also allows you to check for leaks and problems in the spring.
Check coolant and washer fluids for winter. Water expands when frozen and can even crack steel, let alone plastic radiator ends or washer fluid tanks.
A good wash and wax ensures dust and debris come off easily and wont damage paint. If you have driven on salted roads or a lot on the coast, consider washing the suspension as well, as salt corrodes very quickly.
If the car is covered, make sure the cover is properly attached in order to avoid it moving in wind and making scratches. Also take care you don't block your opened windows or suspension ventilation.
Handbrake off, gear on. Handbrakes can, and likely will seize if applied for several months. The handbrake cables can also stretch, so just put it in gear and if necessary put blocks to tires.
Empty the carburetor. On older cars and motorcycles, emptying the carburetor is a good idea to prevent buildups and starting issues.
Remove insurance. Depending on your country, you can pause the insurance and you're not using the car. Savings savings.
These are a few we came up with. All can not be suitable of course, so use if applicable. We hope these tips are useful and save a few hours of work and gray hairs next spring.