I'd say just make sure you greet everyone when you go to a shop. You don't have to go over the top with the greeting, just let it be known that you are there in a quick appropriate manner. I just say to let everyone know you're there, because a service manager I had just a few months ago didn't know anything about fixing cars, but he did spend over $1000 over the span of 2 months on the SO truck buying knives because he was into fishing and hunting, and knives in general lol.
Also, I say let everyone know you're there just because where I work the only trucks that stop by are SO and Mac. The Mac guy comes in, only one guy owes him money, so he just comes in, talks to that tech, and leaves. I don't know if he has a problem with the other techs, but relatively new (about 5 months there) and he has never come talk to me. I guess my advice would be to keep an eye out for new mechanics at your regular stops, talk to them and see if you can establish a good business relationship. I know I would have probably spent a few hundred by now on the MAC truck, but he's never talked to me, besides the one time he threw a flyer on all our toolboxes. So I decide to take any money I spend on the truck to the SO guy, just because he actually comes in, let's everyone know he's there, and will have a decent conversation with us if we're not busy that day. Plus he actually keeps his truck parked in our lot for more than 3 minutes.
So in short, just be polite and let the guys know you're there. Also, keep your truck AC'd on those hot *** summer days lol, my SO guy does, but I could just imagine how much less willingly I'd be to get on a truck if I knew if was just as hot in there as outside on a 98 degree day!
Good luck to you though! Hope you do well on your business venture