(Disclamer: I'm not trained in Ayurveda so this post is just based on what I've learned through my own reading, through consultations with Ayurvedic practitioners, and listening to educational talks from people with training in this field.)
My constitution is vata-pitta, so I try to eat foods that are favorable for both vata and pitta doshas. In other words, I try and find foods that are in the columns of the food chart showing they are favorable for both vata and pitta.
According to Ayurveda, we are all born with a certain constitution called prakruti which is measured in terms of the three doshas - vata, pitta, and kapha. Vikruti, on the other hand, is the current state of imbalances of the doshas in the body. The doshas get out of balance due to unfavorable diet and lifestyle choices. Long term imbalances in the dosha will cause the manifestation of various diseases in the body. You can read a little more about prakruti and vikruti here.
Find out your prakruti and vikruti
The best way to find out your constitution according to Ayurveda would probably be to get a consultation from a practitioner. They can usually assess the prakruti and vikruti by reading the pulse. If you don't already know these, you can get a rough idea by taking one of more of the online quizes -- just google "dosha quiz" and several pop up. You can try the interactive one at the Chopra Center or the printed ones at the Ayurvedic Institute (prakruti and vikruti).
As stated in the instructions by the Ayurvedic Institute, it helps to take the quiz twice, once based on long-term tendencies for the prakruti, and once based on how one is feeling more recently for the vikruti which is why they have two forms. The Chopra Center says the quiz is only for vikruti, but I guess if you filled it out based on long-term tendencies rather than what's been happening in the recent past, then it can be used to get an idea of the prakruti as well.
Finding balancing foods
Once you know your vikruti, you can consult an Ayurvedic food chart to learn about which foods would be best for balancing the doshas. For example, if one finds that one is primarily pitta dosha, then one should try and eat pitta pacifying foods more often than not. Some of the foods are pacifying/favored by all doshas. Such foods are sometimes referred to as tridoshic foods.
Summary
I've found these guidelines to be somewhat helpful for bringing my body back into balance. It takes a long time to heal the body just through diet changes and often the help of herbs may be needed. However, by eating foods that agree with us, we immediately start to experience better digestion.
My constitution is vata-pitta, so I try to eat foods that are favorable for both vata and pitta doshas. In other words, I try and find foods that are in the columns of the food chart showing they are favorable for both vata and pitta.
