Tracing the male or female line
Because of social conventions where it was much more common for the woman to take the man’s name after marriage, it’s usually much easier to trace your family tree via the male line.
Trying to trace the female line can be much more difficult. Historically women were regarded as property of their husbands and they had very few rights.
Basically in tracing the female line you are researching information on maiden names – and these aren’t included on many certificates if you go back a few generations. This only applies to England and Wales. Scottish women usually had their maiden names included on legal documents.
Much of this type of research is better done offline. Are there any family heirlooms? Can you find old letters or anything which might offer clues?
You need to be a bit creative in looking for sources of information. For example, if you know that your female ancestor was a teacher you might be able to find records of her on registers of schools or teachers.
Of course if your female ancestor was an aristocrat you’re likely to have a much easier task. It’s likely that her family crest with have been joined with her husband’s. You’ll need to start researching heraldry.