Here is what comes to mind:
1. A subject that produces visual interest: something that captures the viewer’s mind for one reason or another. The viewer may be drawn to its beauty, its ugliness, its uniqueness, its simplicity or its interest.
2. A dynamic composition that supports the emphasis on the quality being expressed or the stories that surround the subject matter. If the intention is to produce a pleasing image, the composition will also need to exhibit good visual design and balance.
3. Effective use of lighting and/or color. Light and color can come as powerful means to support the messages being conveyed. Evoking visual pleasure in the viewer through the quality of the light, color and balance is of utter importance.
4. You could consider that the final suggestion is encompassed in a combination of all of the above, but to me, the fourth idea is perhaps the most crucial: the degree in which an image can invoke an emotional response in the viewer. An image can express emotion, mood, or perhaps a sense of place, location, or space; how well this is portrayed will add to the quality of the image.
Let me know what you think and be sure to leave a comment.
What can you suggest makes a great photo?