Hi. Should I post suggestions here ?
The one thing I keep adding to GM screens are notes with questions I should ask my players. For example, "is that what <insertcharname> would do ?" or "will <insertcharname> stay here doing nothing and let that happen ?"... Maybe there are a few good ones we could have to help GMs handle specific situations (like helping people roleplay more, ...). That's probably a bit weird but that's something I would use.
I also write tips like "how can this NPS make players shine ?" or "what makes this NPC memorable ?" to remember that :)
Cheers