Hopefully you have already done it.

You need to make sure the batteries are charged. Don't let a drained battery freeze.

You need to empty out all the fresh water. Drain the tank, blow out the water lines.

Many folks will push some RV antifreeze thru the supply lines. That will protect water that collected in the low spots from freezing

Pour some RV antifreeze down each of the drains to protect the "P traps"

On my Logan Coach, there are several drains in the water lines that allow me to drain the lines, the water heater and the water tank. After I drain them, I run the pump and insert a siphon tube into the RV antifreeze bottle and run each fixture untill pink fluid comes out. That way I know there is no water trapped in the line. In the spring I will push clean water through the system untill the pink is gone.

Empty the fridge and anything out of the cabinets that would be damaged by freezing. i.e. Don't leave any cans of chilli or canned peaches in the trailer over the winter.

Just make sure the snow doesn't build up under the trailer...

Most people don't use their trailer enough to wear out their tires. So the usually enemy of tires is dry rot. So there are folks who cover their tires to prevent the sun's ultra violet rays from damaging the rubber of the tire.

If you use your trailer enough to wear out the tread in 2-3 years. I wouldn't worry about covering.  If your use is such that the tire tread will last 10-12 years. Then you need to worry about preventing the dry rot.  Most recommendations that I've seen usggest replacing the tires 5 years, regardless of how tread is left.

For me, I use my trailer, even in the winter.  usually weekly. So it's too much trouble too cover. My tires are worn out in 4-5 years. So I winterize the LQ for winter, but not much else.