To use a telescope, consult with a star or planetary movement chart to determine which celestial body to observe, set up the telescope according to its manufacturer's instructions, and set the telescope's power accordingly. It is not always preferable to use the telescope at maximum power, as this may dilute the resulting image's brightness.
In general, get the most pleasing view from a telescope somewhere around one-half of its maximum power due to the limitations of focus at high magnifications. Some telescopes include special lenses and filters that increase power, but often do so at the expense of the image's clarity.
Another common telescope add-on is a dark filter designed for allowing direct viewing of the Sun. Even with such a device, looking directly at the sun is never recommended. Some of these filters have been known to crack as a result of heat generated by magnifying the sun's light, rupturing the glass of the eyepiece and injuring the telescope user. To observe the sun, use the telescope to project its image onto a white piece of paper or a screen.
One of the most rewarding objects to observe in the night sky is the Moon. It is very popular among amateur astronomers due to its proximity and brightness, as well as the fact individuals can find it without the need of a chart or map.