By and large sticking to the fundamentals works well. Eat more vegetables, grains, fruit. Eat less red meat. Eat more fish, eat less processed food. Dairy has its place, still a bit of debate about full fat or low fat. Reduce animal fat and sugar. Eat more nuts. Eggs in moderation. Alcohol ditto and a bit more. Don’t smoke. There’s a rule of thumb about cooking - you can have fast, good, cheap but only two together. So fast, cheap food is usually not good. Cheap slow food can be good. Good fast food is usually expensive....and so on.