This is a tough area, IMO.
I find working by myself, that I am often needed in more than one place at a given time. If I set up weekly washes (I have some), make sure they are local and set extra fees for further ones.
I try to stress how the paint will continue to look great (safe washing techniques, QD after) and that I do a far better/more thorough job than the carwash for a competitve price. Here's what I include for a "Weekly Wash". Straight from my website:
"
Vehicle’s exterior, wheel wells, and undercarriage washed to remove all road grime, dirt, and soil
All vinyl, rubber, and plastic trim is cleaned then protected (SPF40)
All wheels cleaned free of brake dust and other contaminants
All tires and wheel wells cleaned, then dressed for future protection and a satin sheen look
Entire vehicle receives a 'Quick Detail Gloss Enhancing Procedure'
Vacuum floors, floor mats, and trunk
All seats vacuumed
All dash and door trim wiped free of dust and dirt
All interior windows cleaned with commercial (window tint safe) glass cleaner
All air vents cleaned free of dust and dirt
All door jams and door sills cleaned and glossed