Check your ISO. If you don't know what that means, check your camera's manual. Setting your ISO to the conditions you are in can have a huge impact on your pictures. A general guide is 100-200 for outdoor sunlight, 400 for general purpose (indoors or a shady area), 800-1600 for low light and fast action. The higher the ISO is the grainier your pictures will be, but the more it will be able to capture images in dark rooms.