It really depends on how much time you would like to devote to taking care of your car. Here's what you SHOULD ideally do to keep the paint flawless. Keep this up religiously and your car will be consistently smooth and shiny for 3-5 years before you have to re-polish. And yes, car washes (especially ones with brushes) do create light swirl marks. Brushless washes create fewer swirls, but the high pressure water is hard on the finish and will cause scratching as well.
1. Polish it if it has any swirl marks/scratches.
2. Apply two layers of paint sealant every six months.
3. Wax the car with a paste-based wax every two months. (Yes, on top of the paint sealant)
4. Wash the car once a week on your own. It shouldn't take you more than 10 - 15 minutes to rub the car down with a sponge, rinse, and then dry with a chamois or microfiber towel. Placing the towel down without wiping will help prevent swirl marks and scratches.
Let me know if you have any questions, I detail a lot of cars //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif
edit: LOL at the other posts. This is why I love CA.com