If you want people to RT your posts, RT theirs!
Retweeting is probably the most effective, least selfish way of getting noticed on twitter. Indeed, there are many successful accounts that exclusively rely on RTing for their popularity.
What it means to RT
First of all, it gets you noticed by the person who initially shared the information. Everyone wants to know their tweets are being noticed, and RTing a message is the simplest way of communicating that among all the twitter-litter a message has been seen, and deemed worthy enough to be amplified.