Sorry. Think of a paper trail. Look for primary records ie birth certificates or official governmental birth records, parish registers, marriage records, death or burial records, censuses, Wills. Then you can branch out into land records, title deeds, tithing maps etc. Places to look would be familysearch.org (free), Ancestry (paywall), FindmyPast (paywall), and as you go, you will build up your own toolbox of good sites to visit. FindaGrave tends to be a "See Also" type link, rather than a source.
Most (if not all) Projects have a list of reliable sources.