I would like to eat better for my health too. I have made changes over the last couple of years, such as only eating whole grain bread and rice now, but I would like to keep improving.

I have to watch my salt intake since I veer into hypertension if I don't. So a few years ago, I cut out a lot of processed foods from my diet, since these are rife with salt. I saw an immediate improvement in my blood pressure. No more cup-of-noodles, canned soups, etc. Plus, I cut down on eating dishes that contain soy sauce.

Sometimes I see articles on "best brain foods". Some of the ones I can remember are berries, nuts, fish high in omego-3s such as salmon, and dark chocolate.

ETA: Here is a list I found for best brain foods:

Whole grains
Nuts: walnuts, cashews, almonds, pecans
Berries: blueberries, strawberries, raspberries
Seeds: sunflower seeds, pumpkin seeds
Fish: especially deep sea fish like salmon, halibut, mackerel, sea bass
Green tea
Eggs
Avocados
Tomatoes
Broccoli
Red Cabbage
Eggplant
Spinach
Yogurt
Chocolate: especially dark