As said here before, this is not rocket science, really. Just technique. Let me illustrate with a portrait of a student in my class an hour or so ago:
CAMERA – Set your camera to MANUAL mode. Select, say, 1/125th second at f/5.6 and 400 ISO. This will make the ambient light disappear so the only light is your flash.
FLASH – Use an on-camera flash. Make sure this flash is in TTL mode. Since you are shooting against a white wall, turn flash exposure compensation (“FEC”) to +1 stop.
AIM: Start by aiming the flash straight at your subject. Baaad:
(Just look at the shadows, the deer-in-the-headlight look, the skin, the shadows: Ouch!)
To improve this, now aim the flash behind you, upward at 45 degrees:
Much better. Especially for women.
But for even better results., often used for men, now turn the flash to your right, and still 45 degrees upward. Now you get Rembrandt lighting:
Go try this right now!