For celebrities using Twitter (and social media in general) is a double-edged sword: they can connec with their fans (almost) any time, but everything they say will be dissected or misinterpreted by some people or by all his/her fans.
Celebrities should be careful when using Twitter in special because the message is short, only 140 characters, it’s a lot easier to misled people for whom your language is not their native language. I know you can not please all the people around you, especially as a celebrity, but you should consider that it’s very easy to start a debate if people are upset about some thing or another. One unhappy fan may gather around him other unhappy fans. So, when you are using Twitter be as clear as you can.
As a celebrity you should consider (if you don’t do it already) that everyone is following your tweets carefully. If you write something under the heat of the moment (the influence of emotions) you can tell people something you may don’t want to tell (at least for the moment or not at all) and everything can turn bad. In some cases such things already happened, but I am not going to give examples… you may know some of them and you can always search with yahoo, bing or google for others.
Twitter is a very good method to interact to your audience but don’t let it to take over your life. That’s an advice for everyone to consider, but celebrities should take care more seriously then others: they are followed by a lot of people because they are famous for doing something, not because their activity on Twitter.Managing the time and followers are a must from this point of view.