Before you jump in your car and run off to the first waterfall you Googled in your area, take some time to plan out your shoot first. This is essential to both get the shot you want and to stay safe out on the trail. Waterfalls look best under a diffuse light, so you’ll want to shoot on a cloudy or rainy day, for lovely, consistent lighting. Harsh sunlight can create dappled light and you may get blown out highlights on the falls, which is hard to “fix” in post-processing. There can be some exceptions to wanting to have sunlight in your shot, such as wanting a sunburst coming over the waterfall.
Look up not only weather conditions, but also any potential trail or road closures due to the season. When it is getting close to winter, snow can make a hike more difficult or the road impassible to vehicles. Read up on the trail and pay attention to the length, elevation gain, and any potentially difficult or confusing portions. I always assume waterfalls will be in area of no service, so I will screenshot trail directions, maps, descriptions, et cetera beforehand. Download an offline Google map of the area you will be in, and let someone know where you will be and when you plan on returning. I also highly recommend having The Ten Essentials, which could be split between you and your friends if you do a group outing, and that way you have less weight you have to carry. If you are bringing your pooch, double check whether the area is dog-friendly and what the leash laws are.
Make a checklist of all the gear and outfitting you’ll need and always bring a pair of extra socks! You never know when you will get soaked. If you are driving quite a distance, make sure you know where you will be able to get gas.