Adapted from Scott Kelby's The Flash Book
Kelby, Scott (2018) The Flash Book. San Rafael, CA.: Rocky Nook.
Kelby suggests doing it all manually.
Initial settings for a foreground subject:
camera and flash in manual
flash ¼ power
ISO 100 (min); 1/125th sec; f/5.6;
Take a pic then evaluate and adjust power up or down as necessary.
to change the subject lighting alter the flash power or the f-stop;
to change the background illumination alter the shutter speed, within the bounds of synch;
to change both, alter the ISO.