Here are some of the settings I use on my Nikon Z9 cameras that work for me.
I use the back button focus (BBF) technique (see this post to find out why use Back Button Focus technique) so the first settings I set on my Z9's are related to this:
PHOTO SHOOTING MENU
Focus mode: AF-C - with back button focus, you don't need to change the focus mode for different subjects, you can make the focus work like AF-S (single) by pressing and releasing the AF-ON button, focus like AF-C by holding the AF-ON button.
CUSTOM SETTINGS MENU
a Focus
a1 AF-C priority selection - Release I don't want to wait until the camera thinks the subject is in focus, I want to take the shot when I press the release button.
a2 AF-S priority selection - Release I set this even though I never use AF-S focus mode because of BBF.
a6 AF activation - AF-ON only - this moves the acquire focus function from the release button and to the AF-ON button on the back of the camera - hence the name Back Button Focus.
c Timers/AE lock
c1 Shutter-release button AE-L - ON - if I'm using BBF to acquire focus and want to recompose but don't want the exposure to change, setting this to ON allows a half shutter press to lock exposure.
When I am shooting in the studio with flash lights, the viewfinder would be very dark without changing the View mode. With this set you can see what you're shooting - remember to set back when not using flash so you can see the effects of settings.
CUSTOM SETTINGS MENU
d Shooting/display
d9 View mode (photo Lv):
Show effects of settings - for normal shooting
Adjust for ease of viewing - when using studio lights
These settings are more down to personal preference:
PLAYBACK MENU
Picture review OFF - I find picture review distracting and setting to off might save the battery!
Auto-rotate picture ON
SETUP MENU
Auto rotate info display OFF - The reason I set this to off is because I found it really annoying when using the multi-selector left/right controls to scroll through shots, especially when showing someone else the back of the camera, that one moment the the left/right moves between images, and the next moment is scrolls through the info settings instead - all because I had tilted the camera slightly.
Save focus position ON