I've made myself a couple reference sheets for my D&D campaigns (one for Krevborna and one for Scarabae), and they've really helped me maintain focus on how I want to run my games. Let me walk you through what's on these sheets and why they've been so helpful to me--perhaps they might inspire you to make similar reference sheets for yourself.
The leftmost column has three sections: Goals, Principles, and Actions.
The Goals section is there to remind me, at a glance, what I want my campaign to be about. For Krevborna, this means that the text there steers me toward monster hunting in a Gothic setting. For Scarabae, this means skulduggery in an urban setting. This section is helpful to me because if I feel the game is straying off focus or we're losing site of the campaign's purpose, I can nudge it back into its lane.
The Principles section is there to remind me to keep involving the players (via what they take an interest in) and their characters (via the world-building the players have done to make their characters). When things are stalled out or feeling a little flat I can look at that section and draw on something the players are gravitating to and interject it into the game to get things back in motion.
The Actions section is there to remind me of the things I most often lose sight of during play as well as that D&D can support more than a binary pass/fail system of action resolution.
The center column of both sheets is simply a list of genre-appropriate Names. If there is one thing I find myself grasping for during play, it's a name for a NPC I hadn't counted on needing to name. As new contacts, antagonists, and allies emerge, I need to put names to faces; this column gives me a grab bag of names that I can quickly scan and choose from. I've italicized feminine names so that I can narrow down my scan to get the kind of name I'm looking for. (I tried color-coding the names with blues-for-boys and pink-for-girls, figuring that a little gender essentialism would add visual cues, but it ended up being too "loud" instead of adding utility.)
The rightmost column gives me lists of descriptors.
I have a section for Looks that's helpful when I need to describe an NPC I haven't spent any prep time on; the Looks section is broken down into a subsection about physical appearance and a subsection about what clothing and items the character might have.
I also have a Setting Descriptors section that gives me general aesthetic notes about the campaign worlds' look and feel that I can draw on in play.
This section ends with a list of names for Public Houses (or taverns, or inns, or tea rooms...) because, like NPC names, I often find myself scrambling to name an establishment when the players seek one out and I hadn't planned on that.
(All of this was inspired by the references sheets for John Harper's Blades in the Dark.)