It can be hard to capture indoor lighting accurately. This is due how auto white balance handles indoor light sources. Auto white balance is designed so that whites always appear white regardless of the color of the light source.
The camera also offers preset white balance options for daylight, overcast skies, and incandescent and fluorescent light bulbs. Under mixed lighting, however, you may have trouble deciding which to use. Just as auto white balance will automatically make whites white regardless of the color of the light source, the "Auto 2" option will adjust white balance to preserve the warm colors produced by incandescent bulbs and other indoor lighting.
The built-in flash provides additional lighting for dim interiors, but on the other hand if you use the flash you may lose some of the effect of the interior lighting. This can be prevented by slowing shutter speed as much as possible while still leaving it fast enough to prevent blur. This allows you to capture some of the background lighting for more natural results.
If you use an optional external flash unit, you can also tilt the flash head upwards and bounce the flash off the ceiling for lighting that is soft and natural.