Regardless of the person, the location, or the record, look at the surrounding entries in any record book. If you've found one deed, perhaps a relative had more than one recorded at the same time. If you've found someone in the census, other names on the page may be relatives. If you've found a relative's farm in a county atlas or plat book, look at owners on neighboring properties. If you ancestor obtained Federal land, look at the people who obtained nearby properties.
Sometimes there are clues sitting for the taking in "nearby" records.