One of the most important things you need to consider when buying a telescope is who makes it. A telescope is an astronomical instrument. It is composed of lenses and mirrors that have to be well made in order to function adequately. Remember that you need to gather the light from stars and objects that are millions of miles away. And there can be quite a difference in the quality of telescopes depending on who makes it.
If possible you should get yourself to a place that actually has a selection of telescopes that you can look at and look through. Even if you know nothing about telescopes you can use your common sense when touching and trying telescopes and get a feel for the quality of them. But if you can't get to a place with telescopes in stock you can buy them online from a few different manufacturers that have a track record of making outstanding quality instruments. Here is an overview of some manufacturers that have impeccable quality so you can buy online with confidence.
Meade is one of the oldest and best telescope makers. They have a wide range of telescopes that satisfy the needs of beginners and advanced users alike. They also have quite a big price range from under a hundred dollars to several thousands of dollars. Check out the Nerd's Store for a selection of Meade Telescopes No matter what Meade telescope you buy you can be assured you will be getting a good quality telescope.
Celestron is another manufacturer of fine astromical telescopes. If you are buying a celestron you can rest assured you are getting a good quality instrument. Check out the Nerd's Store for a selection of Celestron Telescopes
Orion is another quality manufacturer of telescopes and telescope accessories. For years orion telescopes tended to be more toward the lower scale and less expensive telescope but in recent years they have been making telescopes that rival other companies in quality and selection and they have kept their prices down. Check out the Nerd's Store for a selection of Orion Telescopes