Some general tips
I've learned nearly everything I know from the following sources. Some day when I have time I may try to write out some more indepth suggestions. For right now, I provide you with the suggestions that got me started, and a few things I've come across on the way.
Wear out your camera - take as many pictures as possible, and then edit and review them. This is your most powerful learning technique which allow you to develop your interest, skills, and style.
Try to convey an emotion in your images. Think about the story or feeling you would like to convey, and then make sure that everything in your photos supports that. You may need to come back at a different time of day, a different season, or under alternate weather conditions - that's part of the game. Try to make your image have sound, taste, and smell, despite it being a purely visual language.
Wherever you are, there will always be something unique about that moment. It usually pays off to emphasize that unique feature and use it to your advantage.
Wide angle landscape photography can be very rewarding, but it can also be very difficult to compose with an ultra-wide (16-28mm on a full frame camera). Think of the focal length as a balance between foreground and background - the more you zoom in, the closer in size the foreground and background, as you zoom out the foreground becomes increasingly emphasized. I generally try two approaches: zoom all the way out, then start zooming in and moving around. Every time you zoom in, change your perspective until everything that was important to you is still in the picture, once you can't zoom in anymore, you've reached your proper focal length. This helps ensure that you have removed the less important aspects, and emphasized the important ones. Alternatively, you can embrace the wide view, and try to put as much exciting material in the photo, this takes a lot of experimentation, as small adjustments with such a wide lens will produce dramatically different results.
And now, some links: The bold links are ones I find particularly useful.