I never believed oily foods and stuff people say give you pimples and oily skin were true, but I saw a big change on my skin after I started loosing weight and eating healthier. Before I always had at least 2 or 3 pimples in my face at all times, and my T-zone was really oily, but after I changed my diet I have had maybe pimple the whole month! That is a huge change!
The foods you should avoid are the obvious ones: chocolate, sweets, candy, deserts, fried foods, heavy and oily carbs. Eat more fruit, a lot of vegetables, yogurt (greek is great!), nuts (not too much) and lean meats. That will certainly improve your skin greatly!!