The lush foliage of a healthy forest needs to be supported by a good water supply, and in hilly or mountainous areas that often means the presence of woodland brooks and streams. Depending on the location, many of these are seasonal in nature, so good timing may be your best strategy.
If possible, I like to photograph these after a fresh rain, and I try to avoid shooting in direct sunlight. That said, you are still likely to get unwanted reflections from the water's surface, rocks, and the neighbouring foliage. Using a good polarizing filter can reduce that glare considerably and help saturate the colours.
A longer exposure can smooth out the flowing water and create that atmospheric silkiness of the water that many photographers like. A shutter speed between 1/4 and 1/2 second is usually adequate. In the darker conditions of the understory this is should be easy to achieve. If it's a bit bright, lower your ISO to 64 or 100, rather than the recommended 200, or try the Live ND feature - a great way of getting longer exposures without the need for an actual ND filter.