I agree with most things you mentioned. The only thing I'd add regarding post length is: don't make it too long either! A post can be super interesting, intriguing, exciting... but if it's so long that you can't finish it in one sitting, you won't ever get to the end of it, where the upvote button is, let alone the resteem or comment ones. I think 1000 words is a good rule of thumb, which I tend to go over or under every time. But at least it gives me a point of guidance.