A strong composition is key to the success of any art piece; it’s what will attract the viewer and keep him or her engaged. Although there are many rules to good composition such as the Golden Rule, the Golden Spiral and the Rule of Thirds these can be thought of as suggestions instead of iron-clad rules.
In very basic terms, good composition amounts to a pleasing arrangement of shapes, colors and tones; but, we are looking for great composition.
Dan Dos Santos does a great job of explaining his 12 pro tips to improve your artistic composition.
To this list of I would add a lead in to the painting such as a road, a river, a line of objects, color, anything that leads the eye into the painting and keeps the eye moving around purposefully.