Generally, the lower the ISO, the less grainy your pictures will be. I was able to obtain good results in very average daylight with an ISO of 100, and a shutter speed of 10 seconds. Obviously, a tripod is required for such pictures.
Crank up the ISO, and in broad daylight you can take pictures with an exposure of less than 1 second.
You will need to experiment with the various settings on your camera. Enjoy!