It always amazes me when I go to a restaurant now, how many phones I see coming out and snapping above a plate of the food they're eating. That's not to say I don't do it. I take photos of almost everything I eat, but just certain tips and certain techniques allow me to get a better photograph, which is quite often what I'm doing for restaurants anyway.
Rule Number 1, is come down to eye level of the food. When we have a conversation with someone, we make eye contact. It's kind of like doing the same thing. We're building a relationship between the thing on our plate an f the person looking at the photograph. We want them to think it's appetizing.
So come down to eye level. Secondly, I'm using my flash, it doesn't matter if I'm using the flash on my camera, or the flash on my phone, but being in nice and tight at eye level with the food and using my flash is creating that beautiful vibrancy and color and light coming in on the plate. The third thing is, play with the food. I'm a big fan of playing with food. I've been doing it since I was 4. What I've done here is have repositioned the spoon with the beans to be in the front with the green of the garnish there. I've got the tortilla chips and the mints, they're on the third level of the rice just hiding in the back.
Anytime you have something on the plate that's the same color as the late, for example, white rice on a white plate, tend to move it out of the focus of the shot. It's generally not going to show up. If you do want the rice to show up, perhaps drizzle some sauce over the top of it, just to define the edges of the rice. But with simple techniques like that, it's much easier to go to a restaurant and take much more appetizing photos to put on Facebook and Instagram.