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.