I don't know much, but I have learned, the hard way, not to wash your car with dish soap. Apparently it will break down the protective barriers in your cars paint, making it more likely to get sun damage - i.e. the paint will fade, oxidize, flake, etc... So if you want to wash it yourself make sure to go out and buy some car washing soap. Taking it to a hand-washing place also seems like it would be okay. And I have also heard you should wax your car like 1 - 4 times per year, so that is also a good idea.

Next time you are at the superstation by your home watch them. How often do they change the water in their buckets? Do they rush? How often do they rinse their sponges? This is what I would pay attention to. Many people are in the car washing business, many do not know how to wash cars properly. Unless you go to a touch-less car wash you will get scratches. How many scratches is up to the washer. Changing out the water in the wash bucket often, gets rid of the dirt particles floating around in the water. These particles are picked up by the sponge or brush and wiped across the surface of your car creating swirls and scratches. Touch-less car washes do a decent job if the car is not that dirty. I live in the northeast where they use salt on the roads in the winter. Touch-less car washes can't seem to get all the salt off my truck. I need to hand wash and scrub it off.

These days most gas stations have car wash as well. Do not allow them to use brushes. Instead choose one which has spray jets and dryers. Some of them will also grease the bearings and the inside of the tires.