Rule of Thirds: should position the most important elements in your scene along these lines, or at the points where they intersect.
Balance/Balancing Elements: Placing your main subject off centre, as with the rule of thirds,
creates a more interesting photo, but it can leave a void in the scene
which can make it feel empty.
Lines/Leading Lines: look at a photo our eye is naturally drawn along lines.
Simplicity/Background:
Framing: The world is full of objects which make perfect natural frames, such as
trees, archways and holes. By placing these around the edge of the
composition you help to isolate the main subject from the outside world.
The result is a more focused image which draws your eye naturally to
the main point of interest.
Avoiding Mergers: