Location
Make sure that you are away from city lights and pollution.
Use a Tripod
This is 100% mandatory. A tripod eliminates camera shake during the long shutter speed that is required to allow enough light into the camera to capture the stars. Any shaking or movement will cause a blurred image.
Camera Settings
These will vary depending on circumstances. But can be predicted within a few variations. These are general guidelines that you might need to tweak for optimum results. Make sure your camera is on manual mode.
- ISO, the goal is to use the lowest ISO possible to keep the photo noise free while getting a well exposed shot. Start with an ISO of 400. If it’s not light enough you will have to increase it until you get enough light coming in.
- Aperture, You want the most amount of light to hit your lens so the wider the aperture the better. Anything f/4 or lower works well.
- Focus, set the focus to infinity.
- Shutter Speed, the longer the shutter speed the more light is allowed in to capture the stars. However if you have the shutter open too long you will get a star trail from the movement of the earth. 30 seconds is a good rule of thumb.