I used to be super anal about detailing and keeping my car perfect. Now I don't care as much. If it looks good from 10 feet away I'm happy.
That said, I do everything I can to avoid swirls. That means nothing touches the car when it is dirty unless it is soapy water for a wash. No spray detail or anything like that unless the surface is 100% clean.
I do the two bucket wash method, too, which is a must. Foam gun, good wash mitts, and two buckets.