A target audience is that specific consumer who would
a. identify with your product
b. be apt to purchase your product
c. would support your product in the long term
That specific market could be 'age' related, profession related, of collectible related. Finding a common thread that interested target audiences would have in common would also be helpful.
Going beyond the identification stages, think of what the comsumer would 'type' in to find your item. Why would they type that word. If it is important and would help a 'targeted' consumer find your products, then that is the 'tag' you should use.
I find on the internet anyone is your potential target audience. It is more important to tag things appropriatley so that person who is specifically looking for your type of product will be able to easily find it.
Some potential buyers- hobbiest, doll house/model enthusiest, teacher. day care worker, parents, children, teens, young adult, grandmothers. Mostly females... Hope this helps you a bit...