When you create a new post there is a Subtitle line just above the main entry area. My suggestion is:
You either blank it, write your post then think about what the main point of your post is and fill that out.
or
Think about what you want to say -- what would help others to know if they want to read it when they see it on an All Topics list-- and fill that out then write the post to suit.
This is good for two reasons:
For you and for others; it helps you focus your post -- it makes it sort of a mini chapter in a story; and it helps others if they don't have time to read everything, or helps them not to miss something interesting or helps everyone find a post days or weeks later. (You can search only subtitles)
Thanks for paying attention to this; way too few people do and a couple of us have a small obsession with this.