Bob Jones has noted that I edit a lot of posts and has asked me to post my style guide so I can be saved some work. Now, I don't mind editing, but that seems like a reasonable idea.
I'm not the only one who edits posts or posts well-formatted questions or answers on the site, though; what aesthetic recommendations do you have for posts? What are frequent formatting errors or typos, etc, do you see? What do you want people to know about formatting and cleaning up their own posts?