A simple way to understand how to chose the right foods for yourself is to first recognize that food is one of the main sources of prana (energy) meaning the purpose of food is to gain positive energy to support our body and mind. Choosing foods that add qualities the body is lacking helps to compensate for the qualities we are missing or don't have enough of. This is why Ayurveda suggests a customized approach to each person. I.e. If a person is experiencing dry skin, constipation and difficulty sleeping this would signal to qualities of dry, airy, mobile, cold from the list of 20 gunas from the Ayurvedic text. Like increases like, so once you identify the qualities of your imbalance, you may chose foods that will provide you with the opposite qualities. With the previous example it would be suggested to have moist, hydrating, warming, cooked, grounding foods. I.e. Foods such as sweet potato, pumpkin cooked in soups, stews and easily digestible forms with spices creating a warming effect such as cumin, coriander, mustard seeds and so on.