For mine own clarity of purpose:
1. There is something interesting to do in every direction. The players know that, have some idea of the options, and can discover the rest of the options through play. They have enough information for each option to make an informed decision on what to do.
2. All of my creative energy goes into making these interesting things to do. There is enough variety that the game doesn't feel repetitive. History, character motivations, relationships, etc are very important, but only if they can inform player decisions.
3. Prep feels like a game rather than a chore. I have a baseline of resources that can be repurposed when working on something new and prevent me from feeling overwhelmed. My methods are fun and efficient, consistently produce interesting material for the players, and don't burn me out.
4. Prep is useful no matter what the players choose to do and supports player agency rather than the illusion of choice. Prepared resources inspire me at the table. They don't allow me to go on autopilot, but they provide enough of a safety net that even when I have an off night the game is still fun.
5. Players don't feel like I am the boss who tells them what to do. They are in charge of themselves and don't feel artificially constrained.
6. Decisions have consequences. There are good decisions with good consequences and bad decisions with bad consequences, and these feel consistent and comprehensible. The rules enforce these consequences and are simple enough that players have an idea of likely outcomes.
7. The rules generate fun and interesting outcomes, whether good or bad. They support rather than resist creative problem solving. They don't get in my way but prevent me from screwing things up too badly.
8. I leave each session feeling energized and with clear goals of what to prep for next time, guided by the notes I take during and immediately after the session. I make sure that, no matter where the players go next, there is something interesting to do.