You have picked a very difficult topic.
Even the FDA found this question quite difficult to answer http://journal.scconline.org/pdf/cc2009open/cc060n04/p00405-p00414.pdf
. (the study is a difficult read but probably worth attempting) and their first attempt entirely failed to get reliable results, and the second approach used HF https://en.wikipedia.org/wiki/Hydrofluoric_acid
which is extremely dangerous to work with and I would not recommend their methodology in a science fair for safety reasons.
Also, the "gold ring test"http://urbanlegends.about.com/library/bl_lead_in_lipstick.htm
is an urban legend, so while it would be easy to set up a "gold ring test" (assuming you have a gold ring), all you could really do with it is try to disprove the urban legend (which would require lipstick with known lead in it, also very difficult to set up as a science fair project).
Unfortunately not every interesting question is a good topic for a science fair project. I recommend choosing a different topic.