What do you do if your surname is very common? This is really a problem because you need to be sure you have the right ancestors. Extra care and diligence in the examination of records will be required of you. If you are researching Edward Doherty in Ireland, you had better make sure you have the right Edward Doherty. To make sure you have the right guy (or gal) you need to make sure you know everything about the person you are researching.

With men it's easier – their surnames usually do not change at marriage. To be sure you have the right man, find his woman. Was your Edward Doherty married to Mary Margaret O'Brian or was he married to Katheryn Kennedy? If they lived in a large city with a common name you have a lot of detective work to do. If John Smith married Sarah Jones in Chicago, you will need to research every one of those individuals until you piece together who belongs to whom. This is time consuming but it pays off in the end as you will be sure that you have the right person. You will have also really polished your research and documentation skills. In this case the littlest fact may be your biggest clue. If John Smith married to Sarah Jones in Chicago was a glass blower, you know that the John Smith married to Sarah Jones who was a baker is not your guy. Check your newspapers and other records for anything that could give you a clue.