Rather then keep a camera's sensitivity set to auto, adjust ISO to improve a low light situation.
Simply look for your camera's ISO setting, you can identify it by looking for such: ISO, auto, 50, 100, 160, 200, 320, 400, 500, 640, 800, 1000, etc.
Depending on your camera type your ISO's numbers will read differently.
The brighter the light, the lower the ISO; the lower the light, the higher the ISO.
(e.g bright light = 100 ISO ; low light = 800 ISO)
In some cases you can avoid using a flash by increasing your ISO.
Hint: the higher the ISO the noisier your image will become