One of the best nutrition advise I was ever given as an athlete by one of my coaches was "read the ingredients before you purchase and eat like an adult"
The first advise is the most simple way to eat healthy and start to pay attention to what is in your food. The second advise is as adults we already know what many bad nutrition choices are for example fast food, donuts, macaroni and cheese, candy these are foods for the most part you just don't want to eat.
Let's talk about Ingredient labels.
Ingredient labels should be simple. 1 - 3 ingredients and ingredients you can pronounce. Once you stop purchasing items with long list of ingredients, for most people the Nutrition Facts sort itself out.
When I started to read the ingredients of the food I purchase I was blown away. The fact is I do not want to put the above ingredient list in my body. So I started to find foods with less ingredients which are also more nutrient dense and whole.
The learning lesson is pretty quick. Look a Skippy Peanut Butter vs 365 Everyday Value, Creamy Peanut Butter
Do this with everything you eat -- look for the best option with the least ingredients and you will Immediately start to make further progress to your health goals.