I'm interested in food photography myself and often read tips on this subject.
1. Use natural light (ideally from a large window).
2. Take food photos with macro lens.
3. Use tripod in order to avoid camera shake.
4. Position food the way that it will be back lit, but don't forget to lift the shadows in the front.
5. Don't shoot from high above (shooting from above working well only in some cases), food looks more natural when shot on the level as if you were sitting at the table.
Hope it helps :)