What is the secret?
Good lighting.
A brightly lit area would definitely make a better food photo. But quality light would make an amazing photo. The best spot to take a great food photo is next to a window. Direct sunlight will look harsh on food and the photo may appear overexposed or oversaturated. Look for light that is soft or use a white cloth to diffuse the direct light.
Then, consider how the angle will allow the light to capture the food in the most flattering way. Always have your light by the side of your food or at the back of your food and never from the front as it will make the food look flat and uninteresting.
So the next time you are in a restaurant or some other space, request a table by a window. And your photos will begin to look better.
There! The secret is out. Now have fun with your food photography adventure.