The thing I feel has the most influence on controlling food cost in my restaurant is training of the managers and crew. Properly recording waste, tracking employee meals, and product rotation are all often overlooked in the process of initial training of employees. Security is another important factor. How easy it is to throw a case of meat under the trash and stick it in your vehicle while you're outside. Staying on top of these things will make a definate impact on food costs.
Communication is another impact.
I have started doing daily inventories on my problem items, and I am zooming in on where the problems are starting. Educate employees on what each product costs, put it in terms of things that they can compare to such as a case of lettuce costs as much as a tank of gas. Also, less visible stock. In other words, the less they see the less they tend to use. Also keep only the amount of product on hand that will be used.