It may be different here in my area, but I do 99.9% of my appointments by phone and email because I do all work alone and by appointment from home. I don't have anyone here when I'm gone on errands, flat glass jobs, etc. so if they show up unannounced, many times there's nobody here.
I only do 0 to a few cars a week, however, because I much prefer flat glass film so my situation is different but I rely on my website, reputation and google reviews to earn trust from first time customers.
If you need to tint a lot of cars then you may need a way to be accessible to people much more than I am.
Having said all that, If you want to make a good living tinting cars, NEVER just give a price when someone asks for it. Try to find a way to create your own style with people on the phone. Get them to relate to you by asking questions, showing them you care about them and their vehicle, use a little humor, explain what sets you apart, etc. One thing I tell people a lot is that I work alone, and spend more time on a car than many busier, cheaper shops do.
Also, don't compete on price, compete on quality.
Doing less work for more money is way smarter than more work for less money.