Waterfalls are by far one of the most popular subjects of landscape photographers, as they can add a nice dose of movement to an otherwise static image, making it far more dynamic and compelling. One of the most crucial choices you can make in this situation is your shutter speed, and this excellent video tutorial will give you some helpful tips for picking the right one.
Coming to you from Photo Tom, this great video tutorial discusses how to choose the proper shutter speed when photographing waterfalls. The shutter speed you choose will have a huge impact on how the movement of the water is rendered in the final image and is something you will want to consider carefully. Beyond that, be sure you are paying attention to the other elements of the frame and how they are impacted by the shutter speed. In particular, if you are photographing in a wooded area, keep a close eye on the wind, as a long shutter speed could end up blurring the leaves around the river. If that is the case, consider making multiple exposures and blending them in post. Check out the video above for the full rundown.
And if you really want to dive into landscape photography, check out "Photographing The World 1: Landscape Photography and Post-Processing with Elia Locardi."