1. Use a polarizer - This is the absolute best tip I can give you in regard to shooting water. The usefulness of a polarizer cannot be overstated. It removes glare and thus helps bring out the most important detail in the colors of the water as well as everything underneath it too. It also cuts the sometimes unnoticeable glare in forest foliage. Adjust the polarizer while it is on your lens and watch the results through the viewfinder or live view. Normally you will try to cut the glare as much as possible, unless you are looking to accentuate reflections and then you'll balance the results. Either way, definitely make sure the filter is screwed on tight enough - so if you pick up or move your camera your filter doesn't take an unwanted spill, which can cost you are very expensive piece of glass.
I used a warming polarizer for this shot taken in the Grand Tetons.
2. Underexpose - This the one type of shot where it will always behoove you to underexpose usually 1/3 - 1/2 stop. Unlike other types of nature pictures, recovering the details of water in large areas of the frame that are blown out or clipped is difficult to recover during post-production. In certain circumstances, a very slight bit of clipping in the water is acceptable, but pay very close attention to your histogram (not your clipping highlight alert) and make sure you err on the side of caution.
3. Bracket - This goes with my underexposure tip. This helps for two reasons: 1) the velocity of water can vary greatly within a frame, 2) typically, forest scenes are busy and darker. This works well with underexposing as larger areas of shadow in your background imagery sometimes narrow the focus to the subject matter itself. However, if you are looking to maximize detail, then bracketing your exposures is greatly beneficial and also can be used as a precautionary measure.
4. Get your feet wet - Many of the best kinds of water images are made from in the stream itself or from a bridge or rock. It's a good idea to own a pair of waders and carry them with you when possible. Please use extra caution when setting up shots from in the water or from slippery rocks as it can be extremely dangerous. Also, you should make sure you photography equipment is insured.
Get Your Feet Wet
Exploring the mysterious, wet, and salty Lake Manly, Death Valley National Park, CA
5. Shoot during overcast days - Overcast days are definitely the best for this kind of landscape photography. If there is any direct sunlight on the water itself - unless you are incredibly skilled in post-processing - you can almost forget about making a high quality image of this kind. If it is a sunny day then you'll have to wait until the sun is low enough in the sky so the water is not being directly affected. The exception to this rule are deep and narrow slot canyons - like for instance, the Narrows in Zion National Park. The indirect and diffused reflections of the sun on canyon walls can greatly enhance the scenery.
6. Look for white water - This is an art in and of itself. Depending on the color and streamflow or channel runoff, certain velocities and volumes of water make for more interesting and dynamic photography. This tip is more about practicing in the field to gain experience in dealing with different types of situations. Sometimes it involves setting up and snapping off a couple of test shots to get an idea of what its going and how its going to look in a picture. You should try to start with the most accessible of areas of the water that have the greatest velocity of flow.
7. Remove the clutter - Maybe not a tip that purists want to read. However, a lot of streams have loose twigs caught in rocks or dead branches laying on the banks in the foreground. Depending on your tastes, these types of items can be very distracting and detract from the overall aesthetics of the scene. Pay close attention to this - if you have the time, and you can safely and effectively remove this from your composition, you might consider doing so. Otherwise, you could possibly take care of it during editing, although it is best to get it right at the time of capture.
8. Look to photograph upstream - Shooting upstream draws the viewers eye into the picture, while shooting downstream can lead the viewers eye out of the shot. One major exception to this is if you are standing on the top of a large waterfall where there are open views leading out. Otherwise, this is a great advice for a general rule of thumb. If you are hiking downstream, make sure you turn around often and check out the views upstream because the scene can look totally different the other way.
Traveling in the backcountry at Great Basin National Park, NV
9. Use a tripod and remote control - I am stating the obvious here, but its importance merits mentioning. If for some reason you don't have a tripod or yours breaks while in the field, you can set your camera on a flat surface like a rock or your backpack and improvise.
10. Use an appropriate shutter speed - This is probably the most advanced tip I have listed here and that's why its last. If you are just starting out - do not concern yourself with this yet. Most people prefer longer exposures thus giving the water a smooth, cotton candy type look. This completely depends on your subject matter and personal tastes. The most aesthetic portrayal of rivers, waterfalls, streams, and creeks can all be different when choosing shutter speed. It all depends on the size, type, and flow of the water. It also depends on what kind of light you are working with, as well as your other camera settings. I explore this topic much more during our workshops and it is easier to demonstrate in the field. If you have specific questions regarding shutter speed, please contact me.
Kitchen Creek near flood stage, Ricketts Glen State Park, PA