Garnish, garnish, garnish
It's the little things that matter, and garnish is an important little thing that makes all the difference when photographing a dish. Take a photo of a prepared meal without garnish, then add some garnish such as a bit of green herbs, or an edible flower, and take a second photo — you'll see right away how much adding just a little something provides the extra flair that makes a food photo successful. This is especially true with foods that are monochromatic, like a hummus or broth, or foods that you can't exactly tell what it is. Garnish can be herbs, or it can be side dishes such as toasted bread next to a bowl of soup, or a bit of salad next to a main dish. Something that adds color, texture and interest to the dish will make all the difference.