A different approach you might consider is to initially show a novelty camera. In addition to your regular (normal looking) camera, carry with you something like a Speed or Crown Graphic press camera. Or anything else unusual. When approaching potential subjects, this is the one you make the initial approach with.
My experience has been that strangers are overwhelmingly fascinated by usually older, novelty cameras. Often to the degree that many will observe you first, then come over and ask you to take their picture with it. I've had this happen to me with a 4x5 Crown. Two young ladies approached me at a state fair and literally begged me to take a picture of one while the other took a picture of me doing so. These two, had I asked them first, likely would have called the police on me as a stalker or pervert.
Once the ice has been broken and a degree of trust established, switching over to your "real" camera is almost never a problem. Just make sure to always offer the subject a print. Beware, however. Once you find how much easier it is to approach strangers with that novelty camera, you might just start leaving the regular one at home.
This also works extremely well with any large format camera. Subjects who wouldn't have given you the time of day if you held up an iPhone will wait patiently almost forever if you are setting up an enormous 8x10. The more different looking the camera, the better the reception you will get.
Here's an example from a Fourth of July weekend a few years back. I was wandering around town with a 4x5 Crown Graphic, looking at all of the various fireworks stands.
At one stand the lady behind the counter literally waved her arms and hollered at me to come over as I walked by. Then she told me to wait until there was a lull in customers. After looking at the camera (she loved the GG screen, as most do), I was pretty much forced by her to make an impromptu family portrait using it. She even made the new customers wait until I was done. And most of them were just as fascinated by it all.
No great work of art was created that day, but I did send them a copy of the result along with a thank you. And I never would have interrupted their business on my own just to make a picture. These people were total strangers to me.
Here is that photograph...