I am not a licensed nutritionist, nor a doctor of any kind, so I offer my own opinion here on eating right simply on the basis of what works right for me. My general belief is that you should eat as close to what nature and God intended. And that the further we depart from this, the more we contaminate our body and decrease it's efficiency.
☺I try not to eat processed foods like boxed flaky potatoes that you pour in a bowl and add water to make mashed potatoes. Flakes of any kind, whether they're breakfast cereals or snacks, seem to go through too much of a rigorous process to be of any significant nutritional value. I think it's worth the extra effort to mash real boiled potatoes and add butter and milk-- and it taste much better. My rule-- eat as close to the whole live food as possible, which means as little commercial processing as possible.
☺Do I eat processed foods? Yes, I don't believe in starving myself eating only raw uncooked foods. But I try to find a balance and realize processing and cooking foods  strips nutrients. The more you heat, mash, grind, and mold food into different forms the less nutrients it will have from its original state.
☺Many processed foods, from health food stores and supermarkets alike, may contain unhealthy additives such as toxins, fillers, and synthetics. I think its important to educate oneself regarding the foods you digest and not automatically assume the producer has your best interest at heart. Junk foods, especially, are made for making profits and not satisfying your nutritional needs.
☺Quickly on the topic of junk foods, I try to strongly restrict eating out at fast foods restaurants, eating bleached foods like bleached flour and rice stripped of its husks, and eating Twinkies, candy bars, sodas, and all the other "foods" that leach nutrients and vital energy from my body.
☺I follow a general eating plan of eating only whole fruits (not juices from concentrate) in the morning. Sometimes, I use discretion when my body feels nutrient starved and I have hot cereal like Wheatena, oatmeal, or other high fiber-- as close to whole grain cereal as possible. But I find that just whole fruits in the morning helps to cleanse my body and gives it all the energy it needs until lunch time.
☺Much of my system for eating I acquired from reading a book called, Fit for Life, by Harvey and Marilyn Diamond.