Landscape is one of the easiest forms of photography to do reasonably as you often have time to think through your options of composition, lens, filters and so on. Obviously, to do this very well requires more skill, a good eye and some practice.
Composition is fundamental to taking a good landscape shot. Many people inadvertantly put the horizon in the middle of the photograph. This rarely looks good. Consider instead placing your subject and horizon using the 'Rule of Thirds'.
Light always play an important role in a landscape photograph and will completely change the mood of the image. By being a good observer of light at certain times of day you can predict light conditions. Remember these will be effected by the weather.
Skyscapes and Sunsets
Sunrise and sunset are some of the most beautiful times to photograph. But the contrast range between the sun, the sky and the horizon provide some special challenges.
The easiest way to get the exposure right for the sky is to aim the camera at the sky right next to the sun, without the sun actually being in the frame. If your camera has an Exposure Lock (sometimes called 'AE Lock') then hold this down while you re-compose the photograph and move the sun back into your frame. The horizon will become silhouetted, but you will get good detail in the cloud and colour range through the sky.