Most classes have to group with someone before they ever have a chance to think about, much less practice, threat management. But we have a built in tank: our pet. We can practice this as clumsily as we need to, dying as often as we have to, all without an audience to mock us. Your pet'll never mock you. He's your best friend! Just don't ask what he tells the other pets when you're not listening.
I'll be discussing "threat," also known as "aggro" or "hate" depending on the group. All of these words refer to one thing: how mad the target is at you and all your allies. Lots of things can cause threat to rise, such as standing within a mob's range, smacking a mob with a gigantic slab of marble, or even healing a party member who is in the process of doing either of those things. Lots of things can also cause threat to drop, such as being feared, being polymorphed, or being killed. Understanding a little about how to manage your own threat will help you prevent that last option from happening to you or your party members.