1. Appropriate light for the subject. If you don't have light that really works with your subject or scene, you simply do not have the basis to begin your composition design.
2. Your main subject matter must be clearly defined. The subject must be apparent. If it can be simply described and is made obvious to the viewer, you are home and hosed! If not, it may not be clear or obvious what your intentions are for the finished image.
3. Your foreground and background must be used as effectively as possible. They can be either clear and sharp all the way through or put out of the scene by changes in aperture setting or focus control. Either way will bring about a different interpretation in your image and you must make that choice.
4. Make sure the weather conditions are right for the intended image you are about to produce. If your intention is photographing close-ups of flower heads and it is blowing a gale outside, then obviously conditions are not okay.
So, before you consider your big shoot, just review this list and be sure it is befitting your photographic situation. Is my subject clear and defined? Is the light right for the subject at hand? Am I able to control the foreground and background to ensure my image is effective? Are the current conditions for me or against me?