How to take indoor photos without them appearing dark.

The best way to improve the brightness, of indoor shots, is to ensure MEGA O.I.S. is enabled on the camera. MEGA O.I.S. will allow for slower shutter speeds (3x slower than normal) and will effectively compensate for hand-shake.

Another technique for improving brightness of indoor shots, is to increase ISO setting. By increasing ISO, the image sensor becomes more sensitive to light and will provide enhanced low-light performance. Select Lumix models have a "High sensitivity" mode option. However, if the shooting environment is too dark, you may need to use the camera's flash (if available) to provide adequate lighting.