The Rule of Thirds - is a technique where the canvas is carved into 3 equal parts both horizontally and vertically. This results in 4 points of convergence where the 4 lines cross over each other (think of a tic-tac-toe grid over the subject you are shooting). It is in these 4 areas that a viewer's eye is drawn to.
Yes, there are always exceptions to this rule (and you should usually trust your gut), but the majority of the time, the Rule of Thirds wins. Learn this single technique and your images will be composed much more strongly and viewers will tend to look at your photos much longer and be drawn in.
The good news here is that humans have a natural tendency to this rule. If you look back through your favourite images that you have taken, you will probably find that many of them adhere to this "rule" without you even trying. It's even been shown that infants are more drawn to images that follow this general composition - so keep the rule in your mind, but don't get hung up on it.
The Rule of Thirds in Landscape Photography
The Rule of Thirds applies to landscape photography, but in a slightly different manner. Instead of carving up the canvas into vertical and horizontal thirds, it's primarily the horizon that is dealt with.
The horizon line is conventionally put in the 1/3rd or 2/3rds area - not in the middle!
If you want to emphasise either the sky or the land, move the horizon to 7/8ths or even more. Again, just do not place the horizon in the middle of the canvas.
Composition is something that should become as natural as breathing to a good photographer.
Practice a lot. Then practice some more.
Think of the photo taken on 9/11 by the great photojournalist, James Nachtwey. He happened to be in New York and heard the commotion on that tragic day. He grabbed his gear and started towards the Twin Towers. When he was a ways off, the first building started to fall, he instinctively raised his camera and got off a few frames. The photo is impeccably framed and composed, he did it in a heartbeat. Your goal should be to be as comfortable with immediately composing an image in your view-finder.
Practice, and you too will be ready to compose great photos at a moment's notice.
Further Photography Composition Resources:
- The Rule Every Photographer Must Know: The Rule of Thirds
- The Golden Section: What a 12th Century Mathematician Can Teach Photographers About Composition
- Using Leading Lines for Captivating Composition
- 27 Images That Break All of the Composition Rules, But Still Rock