Choose your scene. To get a good image of the starscape you should take your camera and tripod outside of the city. Rural locations have less light pollution blocking out the stars and therefore hand greater control to the photographer.
Shoot on a clear night. Overcast evenings are not ideal for photographing the stars. Shoot on a night that is supposed to be clear for several hours. It doesn't matter if some clouds enter your shot, sometimes they add to the dramatic effect, but you don't want complete cloud cover.
Set up your camera. Place your camera on the tripod and point it at the portion of sky you want to photograph. You can include the horizon or treeline for effect.
Choose a shutter speed. The key to photographing the stars or cities at night is slowing the shutter speed enough to allow the light from the stars into the lens of the camera. A shutter speed of around 30 seconds should be sufficient to capture most of the visible stars though you may wish to adjust your settings based on your results. A faster shutter will allow in less light while a slower shutter speed will let in more light.
Select an aperture setting. The aperture can be imagined as being similar to the pupil of an eye. If the shutter speed determines how long the eye is open to receive an image, the aperture is how wide the eye is open. Aperture settings are chosen by "F Stops", a lower number f stop opens the aperture wider while a higher F stop closes the aperture. A good F stop setting for photographing stars is around f 2.8 or f 2.6 which are both quite wide.
Choose an ISO setting. ISO determines the camera or film's sensitivity to light. Since digital SLRs don't contain film, the camera replicates the effect of different film sensitivities digitally. A high ISO setting around 3200 is best for photographing stars because it makes the camera sensitive to any light entering the camera.
Start taking photographs. One of the advantages of digital SLR cameras is that you can review each shot after you have taken it. You can adjust your settings outlined in steps 4 to 6 to experiment with different effects. Because of the slow shutter speed, each photograph will take around 30 seconds to complete.