Probably the most important thing to think about is the light, after all, ‘photography’ means ‘drawing with light’.  

Lighting

Harsh shadows will make your food look un-appealing so the first thing to do is to turn off your camera’s built-in flash and make sure that none of the artificial lighting in your cafe/restaurant is affecting your shot. 

Next find a place to shoot next to a window  (but ideally not in full sun), you are looking for soft even light (think cloudy day). 

If you have sunlight streaming in you can soften it by putting something between the sunand the food to diffuse the light like a piece of baking paper or a bedsheet. 

Now that you have nice soft light on the food from one side you might want to bounce (reflect) light back into the food from the other side, a couple of pieces of white card propped up will do this perfectly.   Your setup should look something like the image below.

Angles

The next thing to consider is camera angle. Phone cameras are very often wide-angle, and this means if you try and shoot the food from a three-quarter angle (the angle that a seated customer would see the food from), it will tend to look distorted. 

On newer phone cameras there is often an option to use a longer lens so use that, or if stuck with a wide-angle, back off from the subject a bit and then crop later for a less distorted look. 

Also on newer phones, you might want to experiment with portrait mode which simulates the out of focus backgrounds you get with longer lenses.

An easier option is to shoot straight down on the food, much less distortion and a good way to show how the food is plated and means that a series of images will look good as a set.

Spend some time learning how to use your phone camera, for example, click on the image to choose where you want the camera to focus and click and drag to decrease/increase exposure. Lastly shoot lots of images, not just the one, try slightly different angles and compositions and experiment with different props.

I hope you found these tips useful, happy shooting!