My answer is based only personal experience. I still haven't located the lineage of my 3ggf Isaac Cushing.
1. Don't just accept a line based only unsourced or poorly sourced suggestions or trees.
2. Start with the ancestor that you have proven by solid documentation is your direct line and find out every piece of documentation you can find about his life. This can help you prove or disprove a family connection.
Do the same with any siblings or other family members you are sure of or need to confirm. Sometimes the will of a family member can be a great help.
3. Locate and research all the other people with the surname who lived in the same area. Family members often lived close and resettled in new locations together.
If you find a likely connection do the research only that family to find documentation to prove or disprove the connection. Even if you disprove a connection, you have increased your knowledge of the family. I encourage you to add what you find here only Wikitree to help others who may be related to those families.
Wills, land records, newspapers, military records etc. can be helpful since you are at the time period before the census or when they didn't offer much information. Also look for family history books published during the time of soon after the time period you are studying for hints. Also town or location historical books. Many are free and online. Some even have a great search feature.
DNA is another possibility.
There is also the possibility that another member, coming from another line of research will find the documents that prove the lineage. That happened with my Susanna Barnett Sorrell brick wall. Out of the blue a user added Zadock Barnett as her father with no documentation and was not anywhere in my research, but I found his will which mentioned Susanna and her husband who were my proven line.
I added and sourced probably a hundred or more Cushing profiles and finally DISPROVED the family I had been sure was the family of my Isaac. I gained a lot of insight and can now fairly quickly evaluate new leads. Hopefully someday I will locate my Isaac 's family.
Good luck with your quest.
