When you take the flash off the camera and put it on a light stand, a whole new world of possibilities open up for you. You're able to position the light exactly where you want it, you can make it more flattering by using modifiers, and you can add additional lights if necessary.
In my just-released Lynda.com video training, Off Camera Flash, I demonstrate a variety of simple techniques that produce absolutely professional results. Check out this short movie for an overview:
By spending just an hour with this course, you can dramatically improve your indoor portrait photography, whether you're on location or in your own environment.