Endings- Know where you are headed and balance repetition and variation. It may change, but try to keep in mind where that final stroke will be, where are our eyes headed.
To be successful, all drama requires opposition. When I paint, I consider everything is in opposition, color, stroke, energy, line, format, shape, subject. Smash things together. Don't be gentle, beauty will rise from and feel the tension of chaos.
Colors should have experience. I'm not a fan of the put it down and leave it school. Get in there and rough it up, get lost, and find your way out through painting, you must learn from the act of painting, give yourself fully.