Best advice I can think of is shop the perimeter of the grocery store, buy food with one ingredient (I.e. chicken, carrots, broccoli, rice, potato, etc.), and then make meals from those ingredients! Too much processed food is consumed today. If you make your own food, that’ll take care of a lot of issues on its own.
Next step would be to watch what’s on your plate. Eat high protein, nutrient dense meals. Limit processed snack food/desserts. And watch your sauces and oils. Lots of sauces make meals taste better, but are loaded with sugar/corn syrup. Seed oils are out, cool with real butter or Avocado oil (olive oil isn’t bad either, but check your packaging, only pure olive oil from on source is what you want. Harder to find at your local Wallyworld)