I used to LOVE Paula Begoun, the Cosmetics Cop, back in the day before I educated myself about Parabens and other dangerous chemicals in our products. I completely disagree with her stance on them and that she uses them in the products she now sells on her website. However, she does put out a useful book to what products work and don't work based on ingredients. It's always an interesting read, but I haven't purchased an updated copy in nearly a decade. On her website, Paula is offering the 7th edition for $5 - the 8th edition will be out soon. She also has a $3 flat shipping offer, so you can get the book for $8. I ordered a copy of it yesterday. I wasn't willing to pay $20 for it, but for $8, I'll bite. That's cheaper than I can find it anywhere used.
Don't Go to the Cosmetics Counter Without Me 7th Edition Link