It's all about lighting. Literally.
The difference between a good photograph and a bad photograph is the way lighting is used. It plays a part in how color is translated, it plays a part in whether a photo is trashy or classy, it can even override bad composition. Hell, you can have a photo that is all dark but has a spec of nice light. Guess what? It'll be nice to look at.
Practice looking at natural lighting and how it interacts with different surfaces. Find interesting shadows while you're out and about it. And if you run into a moment where the lighting is really nice, take a moment to stop and understand what makes it nice.
Photography is the art of seeing. "See" more interestingly and your photographs will follow.
That is the entire premise of Photo Zero. To get the person who's going through it to jump-start their own imagination. A photography course PDF that has information and lessons for beginner and professional photographers.