Acne Prone Skin

Hi There, I Actually Have Mild To Medium Acne Prone Skin Which Is Extremely Oily At Times. Have Always Wanted To Use A Foundation As I Have Never Used It But I'm Unsure What Type Of Foundation Is Best For My Skin. Want Something Would Not Irritate The Acne To Much And Doesn't Look Almost Like It's Been Caked Onto My Skin. Any Help Would Be Great?
Many Thanks