As far as diet goes, you likely have a fair share of bad eating habits. The good news is that most people eat similarly to yours. The bad news is that this is total crap. However, you can switch from a poor diet to one that optimizes body composition by making some key changes and introducing new eating habits.
Given what you've likely eaten, the first thing to do is to attack food quality, with a secondary focus on the timing of the macronutrients. I'll hit you with a few habits and then we'll add more as those become integrated and second nature.