This post is mainly for all the intermediate or better painters out there, and collectors who want to understand the painting process
When one paints more and more especially on one topic, you will begin to repeat yourself and begin to make a formula of how you work. What was unknown when you started is now known in the left brain as information and you start to paint from what you know. To be an artist is a skillful blend of what you know and the unknown. If you let what you know start to take over, your paintings will become more and more trite formulas. Unless you are a Kinkade type painter who makes millions of painting the same thing over and over, even he got bored out of his skull and hired others to paint his works. So how do we counter that trend?
The book Your Artist's Brain by Purcell is good place to start. It will tell you exactly how and why it happens. Then finding ways to access your more unconscious side helps. Here are some ways you can trick that systematic left brain in to letting go more. One way is to make little abstract compositions first, with no subject in mind. No bigger than 3x5 inches, in say 3 colors finding one that pleases you, and using that to plan your work. Robert Bateman the very realist wildlife and nature painter does this, then figures out what animal will fit that composition... Other ways are the informal divisions, not the classic thirds or even Golden section. Painting upside down sometimes shakes things up. Changing two of your main colors on the palette, limiting your palette to 3 primaries and white, or if you are a colorist, painting in monochrome, or vice versa. Switch mediums. And for the last really big box buster. Take one painting and go for broke, not just nice, or OK but either really great or completely busted. Do to it everything that goes against little fixes...get a big brush, scrape it off and repaint parts completely, turn it upside down and work on it as an abstract shape. In short go from the gut and see what happens. And then PAY ATTENTION as you are working to see the effects of what you are doing, brushwork, color changes all the things you know.
You and the painting are dancing partners, you are feeling your way along and listening to what the painting is telling you, not just your mind. If you are dancing with someone you don't push or shove them around, you have a dialog going until the two become one. You are in the moment painting not following along just in the mind but completely alive and aware in that moment, what is really happening, feeling your hand and the brush connect, the movement and sound all of it, really present Now.