I'm a journalist and routinely make cold calls to total strangers. Family history inquiries aren't any different. Make the contact. If people don't respond, don't take it personally.
I've had several non-responses and a couple that were very productive. In one case, they even remembered my father.
But let me tell you about barking up the wrong family tree. I contacted two brothers, believing we were related. One didn't respond, and the other did and was quite gracious. Comparing notes, we found that information didn't match up. I discovered there were three Harry Thomashefskys in NYC, and I was chasing the wrong Harry. I apologized for wasting his time, and he was again very nice about it. I also sent him the history I had written of his grandfather's actions in WWI. I had to delete all the material on the wrong Harry and didn't want it to go to waste. The friendly brother was again gracious and appreciated the information.
So we're all trying to learn, but I find the adventures along the way add to the experience.
Zimmer, Kamiel, Thomashefsky