I have found that a good center of interest in your paintings is vital….it tells the story of what you are wanting to communicate. Here are some characteristics of a good center of interest:
It has the most impact
It has the most detail
It has the maximum value contrast
It also has the maximum chroma
It’s where you place the warmest color against cooler
And….it is interesting. Varying the size and shapes of your subject will help accomplish this.