The Best Tweets Include:
- Recommended links.
- Images and videos to share.
- Something worth replying to and having a conversation over. (Guide to Replies)
- Something worth retweeting. (Avoiding 1-sided conversations)
- Announcements about upcoming events.
- Valid sources of information.
Take a look: http://flatworldschools.blogspot.com/2008/12/twitter-tutorial.html