Be Aware, Read a Label
Awareness is the first step. You need to be aware of what you're eating, what you're cooking, what makes the same foods on the same shelf so incredibly different. The concept that your foods should contain 3-5 ingredients MAX is great guidance, but it's not enough. The more raw, the more natural, the better. The four "steps" below are important for understanding just what's going into your body.
Check the label.
Organics often still include "naturally derived" products. "All natural" does not mean not processed! People often don't get this concept - buying something based on the front of a product but not checking the ingredient list means you have no idea what you're really eating. The front shows "all natural". The back shows ingredients that are "naturally derived". Don't be fooled - it is NOT the same thing. Check the label.
Check it twice.
Processes affect the ingredient list dramatically. Check out standard oils vs hydrogenated oils. Read about corn syrup vs high fructose corn syrup vs corn syrup solids. The differences are critical and the effects on the body can be staggering. A quick glance at the label can overlook these subtle differences. Check that label twice before buying!
Read the label.
Learning the names is critical! One chemical can be described five different ways on different label. Unknown chemicals can be hidden in a generic ingredient in the label, and manufacturers just don't need to tell us what we're eating. What exactly are "natural" or "artificial flavors" anyway? Turns out, you'd be surprised what they can legally contain. If you don't know what an ingredient is, don't eat it (because your body won't know what it is either). Read that label!
Know your labels.
Shelf stable and smooth textured foods are not natural - they've been engineered that way most of the time. Look at the research, read the studies, try the experiments yourself. For example, put a fast food meal in a bag for a year and notice how it doesn't age. Place a stick of margarine in the garage for two months and notice how bugs won't even touch it. And we eat this stuff regularly. Know your labels!
Start with easy steps!
Some things you can do immediately that may help, in addition to reading your labels, are actually related. If your digestive system is already irritated, and it likely is, buy some digestive enzymes to help you digest meals, take some probiotics to start the repair of your intestines, and start avoiding sugar! All these things helped me immensely on my journey, and they still are in use by me on a regular basis.