Make an In-game Learning Tool or Opportunity for a Lesson You Wish More Players Knew
If there's some part of combat -- be it general, role-specific, or job-specific -- that you wish more players were knowledgeable of, could perform, or actually cared about, what is it, and how would you teach it to them?
You're free to make up new forms of learning content or UI, or adapt existing content such as the Hall of Novice or Guildhests, as you see fit.
Package these lessons together if you feel they're best taught together. If you have no specific lessons you want to teach, but have a lot to say about means by which those lessons could be taught, go straight for that instead.