Turn Left at Orion is a popular suggestion (see sibling comment) but the other question is what do you want to do, what part of astronomy interests you? Amateur astronomy is a vast field and depending on what you're interested in, you'll go in different directions. Do you want to look at the Moon? Planets? Galaxies? And so on. Of course, you probably need a starting point which a good book can provide. See if you have a local astronomy club you can go visit, they will usually have events where you can use telescopes and talk to experienced folks. You can also poke around on Cloudy Nights (www.cloudynights.com), by far the largest amateur astronomy forum online.