It is actually quite simple. The diet I have tried was made of mostly whole grain, lean and high protein, lots of veggie and some fruit.
For whole grain, I try to eat everything whole grain. From whole wheat bread, to brown rice, quinoa, buck wheat.
For lean and high protein, I prefer steak and salmon. Sometimes I also eat chicken breast. Basically high quality protein with little or only healthy fats.
I also do not have sugar at home at all.
I also drink only fat free milk and yogurt.