For those of you with a black car, there is a preferred way to wash your car, but I don't know how you would wash a car below freezing.
Since I am not so young anymore, I don't wash my car by hand nearly as much as I should. The result is swirl marks that require a good polish a couple times of year to keep at bay. In any event, waxing your car 3 to 4 times a year is a must. Do it at the change of the season, make it an event. Your paint will thank you for it.
The proper way to wash your car.
Wash your bucket. Dirt left behind by a previous wash will scratch your paint.
Use soap meant for washing cars. Dish soap is meant to strip grease and wax, and will leave your surface unprotected.
Get a lamb wash mit.
Fill your bucket with water and soap in the prescribed amounts. Wet your car thoroughly and soap off the hood with your mit. Rinse hood, then blast the dirt off the mit. Make sure you blast the dirt off BEFORE it goes back in the bucket.
Next panel is the roof. Clean the mit again.
Next is the trunk, clean mit after every use. See a pattern? The idea is we don't want to contaminate the soapy water we are using to wash our car. Never put the dirty mit into the bucket!!!
Now you can get the front, and then wash one panel at a time on the sides. Ideally you want to go from top of the panel down, as the panels are dirtier on the bottom.
When you are done washing all the panels, rinse your mit and put it away. Now grab your sponge and clean the rims with the leftover bucket water.
Dry car with a good chamois. I like the synthetic versions as they hold way more water. You don't want to rub any part of the car, just drape the chamois over an area to soak up water.
The final step is to use a QD spray. I like meguiars, but any QD spray will work. Make sure you use a microfiber cloth and constantly rotate the surface as you work over the car. You should use 3 to 4 cloths completely to cover the car. Wash your microfiber cloths with your laundry when done.
You can find this procedure on most car forums, and any detailing site. The end result should take you 2 to 3 hours, but the car will look amazing!
Oh, and if its time to wax the car, wax the car before you QD it. For the ultimate shine, you can clay bar before you wax. I did this entire procedure (clay bar and wax) when we first bought the Camaro and I literally wept when I was finished, the paint looked so good!!!