I think what makes GM advice, and GM principles and moves feel so difficult to put together sometimes is that its hard to Articulate the ways in which you as the designer feel the game should be played into instructions that feel specific enough that they will always work while not being too specific and restrictive, and that properly represent the feeling you want to replicate.
Something that I think works well for thinking about principles, moves, and specific instructions is to think about what you would do as a GM in a variety of situations, test play the game a few times if you can, and create a list of what you did/would do then work backwards from there. Think about what you did, figure out why you did it (i.e. if you describe "the dragon as it emerged from the lake in the distances red scales glittering as it launched into the air in a spray of mist" did you do it to " Show them a dangerous creature nearby" or to "show them something fantastical in the world") and build a list. Once you're done you should have a list of things that sound like moves you made, go through and clean them up, see if any are similar or can work the same, and add some flavor to any that sound particularly boring (i.e. "Make an enemy appear" becomes "Have a monster burst forth!")