Pollan's excellent advice to eat food, and not too much. Food meaning something that our great grandparents would have recognized as food.
The screenshot on the right is from the excellent iPhone app Loseit. It is very effective and free. There are many tools like this to help you if you need it, but simply being aware of what you eat and not eating as much as you might normally works just fine too.
Now I just need new New Year's resolutions for next year.