When taking a picture with your camera, if you are intent on getting a good overall image then you should try and think about the rule of thirds when creating your composition. Sometimes when taking a picture, you don’t actually have too much time to think about exactly what you are seeing int he viewfinder but in time, with practice you will automatically create images that will usually correspond to the rule of thirds.
So the rule of thirds basically points you in the direction of where the focus of your image should be. In basic terms, you would divide the picture up into 3 sections both horizontally and vertically and then your main focus point of the image would be near one of the crossing points of the thirds (see image below)
If you look at any of the great photographs or even great paintings then you will see that in some way, whether consciously or subconsciously the rule of thirds has been applied and the focal point of the picture is not in the middle.
You can also make use of the rule of thirds when creating some kind of landscape – i.e. do not put the horizon right in the middle of the picture but instead put it around a third of the way up (or even down). It doesn’t necessarily have to be exactly a third, but putting it in the middle does not lend itself to a great composition.
To see if you are really using the pule of thirds in your pictures, add a grid over the top and see which photographs have used that rule and which have not and decide which ones look better.