Be sure to carry a range of filters with you. Reflections can often be several stops darker than the main foliage. If this is the case, use a graduated neutral density filter to even things out. A solid ND filter will enable you to lengthen the exposure to smooth out water ripples in a breeze. Lastly, a polarizer will reduce the amount of glare hitting the water, while also giving contrast and saturation a little boost.
For autumn scenes, use a tripod to ensure you capture shake-free shots