Try
Focal length : widest
Mode : Manual
Shutter Speed : 1/60sec
Aperture : f5.6 to f8.0
ISO : 800 to 1600
Image type : RAW or JPEG
Flash Head Position: For low ceiling, tilt the flash head 60/70 degree upward with bounce card/diffuser. For high ceiling, flash head direct.
When to shoot ? Say '1' and shoot. Some people tend to close eyes at count number 3.