Along with shutter speed and aperture, ISO is one of the three fundamental exposure parameters that have a significant impact on the technical quality of your image and on the creative decisions you can make. If you are new to photography and feeling a bit unsure about how to handle your ISO, check out this helpful video tutorial that takes a very pragmatic approach to the topic with five useful tips.
Coming to you from Nate Torres Photography, this awesome video tutorial features five tips for getting a better handle on using ISO. By far, the most common mistakes beginners make with ISO is simply keeping it too low in an attempt increase image quality and using too slow of a shutter speed as a result, which causes issues with blurring from camera shake or subject motion. The important thing to remember is that modern cameras handle higher ISOs very well, and post-processing software can do quite a bit to clean up noise. On the other hand, if a photo is blurry from camera shake or subject motion, there is not much that can be done to fix it. It is always better to have a noisy but sharp photo than one with less noise but issues with blurring. Check out the video above for the full rundown from Torres.
Good video. I think the comments about keeping the ISO too low are spot on. These days, especially if you have even a middle of the road full frame sensor camera, you can push up to 6400 easily, which when you think about the sunny 16 rule means you can get 1/6400s exposure in full sun at f/16, so in the depths of darkness you're probably looking at 1/30-1/60 which is more than ample for most focal lengths to avoid camera shake.