Reduce your intake of alcohol and tobacco. Both of these items cause major disruptions in our biochemistry and are leading causes of death in America. Eliminate or drastically reduce processed grains as much as possible. This includes white bread, pasta, biscuits, cakes, pizza, etc. You can eat whole grains but be careful.
Many people are allergic to wheat and other grains.
Try to eat protein at every meal, especially breakfast. Protein is a very stable energy source. This will stabilize your insulin levels and foster proper neuron functioning. Soy products, lean meat and fish are good protein sources. Eat lots of vegetables.