To answer some questions I received privately.
It sometimes take months for someone to reply. Some never do.
I have an extensive tree. I know the names of all my g g grandparents. I have identified many (most) of my g grandparents' siblings.; for 5/8 I am confident I have the names of all siblings. Thus I sometimes recognize the names of many potential matches. Through names or common matches I can usually tell which branch (at the g grandparent level) they are on. When i don't recognize the name I try to find the match on social media to see who their relatives are or where they are from. When i contact the match I tell them how I think we are related and often ask if so-and-so was their parent or grandparent.
Finally, most branches of my tree spent time in Fall River, MA, so I ask if they have any ties to southeastern MA or Rhode Island.