I used Connelly's book BODY RX when I went shopping. He divides foods into Red, Green and Yellow foods....ie. Red eat rarely, Green eat as much as you'd like. I took the book to work and photocopied the food lists and then circled the foods from the Green and Yellow list that I'd actually eat. (The Red list has all the "good" stuff so I'd circle the whole list if I could, hehe).
I'd take the lists to the store with me and go from there! Sounds like alot of work, but it's not and has helped me avoid making bad purchases on those days when I all want is to buy everything in the potato chip aisle!