Family histories and genealogies can be a great help. They can also be a problem.
Here are some guidelines:
1) Check the date of publication. Earlier works may need a lot of follow-up and may have relied on some shaky research.
2) Look at the sources cited. Some may be questionable, others reliable.
3) Realize the author's focus. Does the book focus on the surname, one particular line, one individual's family?
4) Read between the lines. If probably, believed to be, or similar phrases are used with lists of children, the author may not be sure that child belongs where assigned.
5) Pay attention to places. If a child doesn't fit geographically, he/she probably doesn't belong. Likewise, look for locations in relation to the family migration. If they arrive in Indiana before 1776, there is likely something wrong.
6) Watch out for incorrectly identified progenitors. Make sure the fellow who begat the family really begat the family.
7) Make copies of pertinent pages so you can refer back to them later. You might have missed something.
8) Check more current sources for new details that might not have been available at the time of publication.