Keep in mind the time of day. Photographers look for "sweet light," early morning or late afternoon when shadows delineate form in dramatic ways.
Don't think you just need a bright, sunny day. An impending storm or the clearing right after a storm can offer spectacular lighting.
Take a lot of pictures. "That's easier now with digital cameras."
Match the equipment to the subject. "Digital is great for some things, but film still works better for others. You can't use digital for nighttime, time-lapse shots, for example."
Get off the beaten path. Some of the best shots are away from the road or at least out of the car.
Follow common sense and safety rules. Don't risk your life for a great picture.
Don't get so caught up in the pictures that you forget to enjoy the setting. Take time to look around and savor what nature has to offer.