I think a lot of women go through this problem because of hormonal fluctuations and stress, which can take a toll on the skin.
The best thing to do is to use a cleanser that's extra mild and made for combination skin.
http://www.bewellstaywell.com/skin_care.htm http://www.jason-natural.com/products/oily_skin.php
http://www.aveeno.com/productListAction.do?sid=1000
Limiting refined sugar in your diet is helpful too (candy, soda, alcohol, bread, etc..). Too much sugar can definitely cause problems like acne, redness and inflamation.
White and green tea is very good for your skin also. It flushes out toxins and other impurities.