Hold the Camera Level
A basic rule of photography is to hold the camera level. Since most digital cameras come with a LCD, you can use it to properly frame your shots. Next time you're taking a shot, try to look for the horizontal lines and use them as guides. A good example is to make use of the horizon when you're taking a photo of a sunset.
When shooting landscapes you usually want everything in focus all the way to infinity. Therefore, you will want to use as small an f/stop as your camera will allow.
You should use a wide-angle lens setting and consider adding a foreground object to help draw the eye into the photo. Experiment by isolating different portions of the scene using an optical zoom lens. And of course always apply the law of thirds.
Steady the Camera for Sharper Pictures
The key to getting sharp photos is keeping your camera steady while pressing the shutter button. Digital cameras are so light that special care is required to hold them steady during shooting. Squeeze the button very gently, making sure you don't jerk the camera as you press the shutter button.
Sometimes you will want to simulate movement such as a race car going by at a racetrack. Use a fast shutter speed or pan the camera to follow the subject to maintain focus. Done correctly, panning will keep the subject clear, while blurring the background, giving the impression of motion.
Position the Horizon
where you place the horizon in your shot affects what is emphasized. To show the land, use a high horizon. To show the sky, use a low horizon. Be creative.