From The Morning News, some basic recommendations on the etiquette of Twittering; Fourteen Ways to Use Twitter Politely.
Written by Margaret Mason, author of "No One Cares What You Had for Lunch: 100 Ideas for Your Blog", the article is "not about the things Twitter does, it’s an article about the ways in which you can accidentally annoy people with Twitter. Should you choose to avoid Twitter, that’s fine."
To start you off...Rule 1). Watch your ratio. If only a few people follow you, but you follow a thousand or more, many people will assume you’re a spammer. That’s because you probably are. Go away, spammer. We do not care about your Facebook app.