If your friend has some behaviors that you want to "cure" or change, communication is key.
If she's being overly jealous, have an honest conversation. Let her know how her jealousy makes you feel and that you value her friendship and don't want this negative emotion to affect it.
If she's a bit of a drama queen, try to be a calming influence. When she starts to overreact, gently point out the situation rationally and encourage her to look at things from a more objective point of view.
If she's too clingy, set healthy boundaries. Let her know that you also need some personal space. But always reassure her of your friendship and that having space doesn't mean you care less about her.