It is not a mortal sin when one already has oily skin!! That is such a skin trap from the cosmetic people. I only use sun screen everyday, and even then, I need to be careful. I have found a line that I love and it very reasonable.
Since I do have oily skin, I have done a lot of research on skin products. I found a book called "Don't Go the Cosmetic Counter Without Me," by Paula Begoun. She is like the consumer products guru of make up and skin care, and gives you the low down on everything. It's about 1400 pages.

Even what big company owns what, and what products are just as good from a drug stores verses the department stores. I love it, and have finally found a system that works for me. She also has a website.
For instance...Pro Active...she will tell you what is just as good or better that you can find in an drug store. Or that L'Oreal owns Lancome, Maybelline, Helena Rubinstein and so on. Este Lauder owns Clinique, Stila M.A.C. and so on. And so much more.
Geesh can you tell I like this kind of stuff.
Also that I type slow?