Here are some tip of Twitter Etiquette.
Do not tweet continuously. Sending lots of tweets in a short period of time is just annoying.
Do not use DM autoresponders. More often than not, DM autoresponders are used poorly. It does get rather annoying when someone DMs you a thank you and some other important DMs get covered up to several pages later.
Do not beg for retweets. If your content is good, other Twitter users will retweet it. Asking "pls RT" makes you look desperate.
Do use CAPS to help other tweeps understand your message. VIDEO: www.youtube.com/xxxxxx. IMPORTANT: MJ has died!
Do not autotweet. Autotweeting is usually a bad idea.
Do not follow the "join to get 400 followers." It makes you tweet the same tweet over and over and there is no way to get off it. (Except changing your password)
Do not overuse the HASHTAGs. Hashtags can be extremely useful but they're frequently abused by spammers, marketers and applications. So choose which ones you use wisely. Hint: hashtags relating to body parts, private matters, illegal activities and words you wouldn't use in the presence of your grandparents are usually the ones to avoid.
Do not use random characters with numbers behind for your user name. If you have just started an account, it is not too late to change it now. You may look like a spambot, even though you're human!
Do not tweet nothing but things to sell or squeeze pages. This is 'social' media. Just as nobody likes the person who is constantly puts links to squeezpages or clickbank stuff. Provide value with your tweets.
Do not overfollow or autofollow. If you have 500 followers but are following 5,000 people, something is wrong. Some people have sophisticated beliefs regarding follower ratios.
Do not sell out. Tweeting a message for a company for a chance to win a free laptop may be a good deal for the company, but by tweeting marketing messages for compensation (or a chance at compensation), you send the message that you're easily bought and sold.
Think before you tweet. 140 characters is not a lot, sending 3 tweets to make 1 message just does not cut it.
Do not send just a link without a description. With url shorteners, who the hell knows what you are tweeting about?
Follow these rules and you can become a better tweep!