I can never write in one sitting.  I envy that.  That's a skill.  

I go like:
Vague outline for a posts progression.  Fill out the paragraphs.  Take out excessive stupid jokes and innuendo.  Grammar.  Spelling.  Add in something where several words that start with the same letters follow each other like a dumb discount V for Vendetta.  Never actually post until someone points out that I'm holding shit up.