I will say that the rules (and thus some of the GMing assumptions) are changing a little in the latest version, but core Apocalypse World et al. guidelines apply to GMing, since that's my preferred style, what I'm aiming for with the game, and what the game its kind of based on (John Harper's Blades in the Dark) does best: 1) Start with a bang, but let things go where they'll go after that. 2) Fiction first! Let everything, including rolls, dangers, challenges, Scale, etc. flow from the conversation you and the rest of the players are having at the table. 3) Have some basic prep (a cluster ready to go, maybe with some ideas for dangers, opportunities, or factions jotted down), but don't go too far before play begins - you don't know where play will take you, so run with it! Check in with your prep after every session or couple of sessions to make sure you're keeping things straight or to embellish stuff/push the pieces around as needed. Don't spend too long on this. Roll dice to figure stuff out if needed. Rinse, repeat. 4) As always, be a fan of the player characters, and play your NPCs like you're taking joyrides in stolen cars.
The game as is on this page isn't the friendliest game to run or play, but that should be remedied in the next version. Lots of changes to come!