The clue to seeing is the simple act of squinting with our eyes so that no details of our subject are visible. But it's one of the most difficult of things to get an emerging artist to do. Everybody wants to jump right in and begin painting before taking a good look at what's there.
Try this. Look at a bare tree trunk and its surroundings. What do you see? Gray, black, brown?
Now squint your eyes so that all the details go away, stare at that tree trunk through your squint and hold it for a whopping ten seconds.


Then, practice gathering information through the squint. What colors emerge? What values are those colors? Here's where the real truth of harmony lies. Below I've done a sampling of each value area.

I can do a painting of the entire scene with variations of these three colors. If I want to make the scene a bit more expressive, I can exaggerate the components of these colors.
I've discovered that these are mixtures of oranges and purples. Here's where I find the harmony and here's how I arrive at my color scheme. It's all out there to be discovered.
Try the above little exercise. Do it several dozen times--until it becomes habit--and you will find how easy it is to get into the habit of squinting in order to discover the harmony of your subject.