How much light is there?

in daylight, use the "better" apertures, such as f/8-f/11. By doing so, you will also get more depth of field, and more of the frame will be in-focus.

in doors, first set your ISO higher. ISO is commonly overlooked. Widen your aperture to between f/1.4-f/6. Different lenses have different max apertures.

What you are trying to do here is get an acceptably fast shutter-speed. Heres a basic rule of thumb: Take your focal length and double that.

That's what your shutter speed should be to ENSURE a sharp images. Example: You are shooting at 50mm. Use a 1/100 shutter speed.