To retweet is, according to Wikipedia, to 're-post something posted by another user on the micro-blogging service Twitter'. Standard retweeting, ie clicking the 'retweet' button on Twitter.com or various Twitter clients, is easy enough. One click and the original tweet is automatically retweeted. Old school retweeting, ie copying a tweet and adding 'RT @username' to the start is, however, an art all of its own. Both versions need to be used with care. So here are some words of advice for the discerning gentleman or lady retweeter.

• Editing: Do make sure the retweet makes sense to someone who may not have seen the original tweet in context. For instance a retweet of 'It really is bright tonight' could become 'Venus really is bright tonight'. Some light editing, such as changing 'and' in the original tweet to '&', to allow for the Twitter character limit is fine. As for correcting spelling and grammar, well I'll leave that to your discretion. Obviously, try to keep your retweet, including the 'RT @username', within Twitter's 140 character limit. (Old school RT only)
• Commenting: Enhance a retweet by adding your own comment. The syntax '<-- my comment' at the end of a retweet is standard practise. (Old school RT only)
• Frequency: Don't retweet too much. An account with nothing but retweets is a bad thing. A retweet should mean something, it should be a recommendation to your followers, not a dumb reposting of another user's content.
• Privacy: Don't retweet someone who has protected their tweets without asking first.
• Multiples: If you are retweeting something that several people have tweeted about, a web link for example, try adding '(via @username1, @username2)' to the retweet to give credit where credit is due. (Old school RT only)
• Client: Choose a Twitter client that allows you to do 'old school' retweeting as well as standard. Most decent ones will.
• Uniqueness: If you want to retweet the latest blog post from @stephenfry or suchlike twitterati then fine, but hundreds of other people will have already done so and all your followers probably follow them already anyway. Try to make your retweet something different, shining a light on a gem of a tweet that may have passed others by.