What are the tips for using internal flash with a 50F1.8 lens when taking portraits at an auto show?

Generally, I use M mode, set the shutter to about 1/75 (following the safety shutter rule of faster than the reciprocal of the focal length), and the aperture is fully open. Use center-weighted metering, and the flash exposure compensation needs to change according to the scene conditions. If the background light is very low, then you need to reduce the compensation by 1-2 stops. If the background has a very bright point light source or is very bright, you need to increase the exposure compensation. As for eliminating the shadow of hair on the face, if the hair hangs down from one side of the face, then the top of the camera should not be facing that way when shooting vertically. If the scene light is very strong, causing ugly shadows on the person's face, then you need to increase the shutter speed to darken the background and reduce the interference of the scene light on the person.