Start with a shutter speed set at 1/60th of a second. This is a fast enough speed that the image is unlikely to blur but slow enough to produce a bright and vibrant image. After an initial test image, increase the speed if the image is too bright.
Shutter speed works in combination with film speed and f-stop. A higher film speed will produce brighter images but with more grain. A lower f-stop decreases the depth of field but increases brightness. Adjusting these two setting along with adjustments to the shutter speed will produce well lit and crisply detailed images. You can also use a slow shutter speed to produce effects like motion blur.