Don't assume that people will keep things private
Do not be afraid to take time in deciding how much information you want to divulge to certain people. While you generally should be as open with your immediate family as possible, when it comes to acquaintances and friends, the ball is in your court. However, it is important to realize that telling someone about the condition is not easily undone. So, if you want to tell one friend, but absolutely cannot have another knowing, you might want to rethink your decision. Word gets around quickly, so assume that the people you are telling are not the only people who will be learning of the information.