1. Don't tweet Multiple @s or Puts too many @'s in one tweet, it's ok to do it- just don't let it be the only type of tweet you do! This is considered dodgy behavior!
2. Don't tweet nothing but links.
3. Don't tweet the same links all the time.
4. Don't tweet the same tweet over and over.
5. Do mix up your tweets- text tweets, link tweets and tweet replies and keep it relevant to your brand or identity.
6. Make sure to have recent activity i.e tweets! Don't let your account go a month with out activity
7. Do have more than 10 tweets! And build your tweets to reflect your brand and identity!
8. What not to do- Don't Interact With Anyone or Never interacts with any of their followers
9. No no's-Hardly Follow Anyone (People that follow back less than 10% of the people who follow them) who is guilty of this? @oprah
10. Don't send out a bunch a tweets or the same tweets all at once- your followers will appreciate it!
    

The important thing to remember is to use a variety of tweets and you will be more likely to keep your following on Twitter.  Want to see which of your followings and followers are guilty of these no no's check out http://thetwitcleaner.com. I invite you to comment on your own user experience on twit cleaner.