1) Where is the light source?
2) Where is the horizon located?
3) Is there a hierarchy of shapes?
4) Negative shapes?
5) Color or Mud?
1) Know which direction the light is coming from. Take a quick reference photo or make a small thumbnail sketch. Being aware of the difference between dark and light and the cast of the shadow will give your painting three dimensions.
2) Remember the golden rule! Use the division of thirds.
4) Negative shapes are actually what makes your painting work. Some artists work only on the negative shapes, ignoring the positive to get a fresh and unusual perspective on their work.