Frame Your Foods Well
After deciding what you want to photograph, consider cutting it into geometric shapes instead of disorganized blobs. (Have you ever seen a professional photo of a slice of pie that wasn't triangular in shape? I didn't think so.) You can also consider stacking foods like turkey slices on top of each other to add more dimension to your photo. Of course, you'd be wise to include some form of contrasting garnish to your dish to not only make it appear tastier, but also offer more visual contrast. Try to find a food that is a contrasting color from the main subject to offer even more pop.
A general tip: You'll also want to make sure that your photos fill the frame completely. Get as close to your subject as possible and don't leave a lot of extra space in the image. This will not only make your photos more appealing, but will allow you to capture more detail of the foods you're trying to photograph. If you're using a digital camera as opposed to a smartphone, consider using a macro lens when you get up close with your food shots to capture all the details of your delish dish. Most point-and-shoot cameras will offer the macro lens feature, but if you want a macro shot on your smartphone, this macro lens in an elastic band is the perfect companion.