The old standby statement "live in the moment" rings especially true in nature photography. Being present means being mindful, aware of the weather and how the conditions effect the subject you are photographing. How is the vegetation reacting to the conditions, are the animals and birds still present? Being aware of smells and sounds also adds to your own experience which is subtly passed along in the image. Passion and love for what you are photographing is immensely important to the end result.
I believe honest nature photography comes with inherent morals and ethics, above all else respect and love what you have been given permission to see. Understand the intricacies of the life around you, do no harm, and do not ask anything of nature that is not given freely.