As mentioned previously, the likelihood of being on the other end of a retweet increases as you retweet. Retweeting someone else’s content is an act of kindness, and for the most part bloggers like to return such acts. This isn’t to say that you should expect someone to retweet your content just because you retweet theirs. (Blogging Bits)

There are no set rules about when to retweet, but in general, you should retweet when you find something particularly interesting or noteworthy. (About.com)

If your original post is close to 140 characters, the person retweeting has to edit your post to send it back out. Smells like work? People won’t make extra effort to retweet you if they have to edit your posts. (Chris Pearson)