Look for the strongest DNA cousin on your father’s side. Then look at all their shared matches, and start looking at their trees for a common ancestor. If they don’t have a tree, message them and ask how they relate to another match. Most won’t reply, but at least one might. Make lots of notes and draw up their trees. Group them into your paternal mother’s side, and paternal father’s side. If you don’t know which is which, just family groups based on shared matches. I did this and found that the father of my grandmother was one of two brothers. DNA from half 2nd cousins does not point strongly enough to which one. I also surprisingly discovered my grandmother had an affair which resulted in my father and one of his sisters. I have also found grandparents etc for friends. Sometimes it’s really fast and easy, but other times you have to wait for a “smoking gun” to show up, ie. a half 2nd cousin from that side of the family. Good luck.
