I also find that is not simple to add tags. In previous conversations, they advise:
-think for how is it for? children, mothers, etc
-dimension
-particular colors
-for which occasion
-use ONLY one word per tag
Hope it could help you, I also try to test these kind of tags with my news items. Will see if it works!
A last advise: maybe if you can find someone with similar items of yours you can check which tags they use...
Good luck!