What am I trying to say?
Constantly ask yourself this question while in the process of writing. Unless you have a clear idea of what you would like to say how are you going to write it? Once you have formulated what you wish to convey to your writers your thought process will automatically get attuned to that idea and words & sentences will flow together to put your idea into action.
What words best express my idea?
Once you are clear of what you want to say, choose the post appropriate words so that the meaning behind your idea is conveyed most effectively. Vague words will leave your readers feeling left out and confused. Precise words will make them feel involved and interested.
What image or idiom will make it clearer?
Here you have to make sure that your description of your idea is accurate. Look for phrases that are apt and closely follow your idea.
Is this image fresh enough to have an effect?
You may have described your idea beautifully, but are you sure that has not be done before? Try using new and innovative ideas/images/phrases/idioms to convey your thoughts. Think outside the box.