It occurs to me that after that first tip, there is no order of precedence for the rest. I'm calling this Tip #2, but most likely it's not more important than Tip #34 will be.
Here it is: Know your story inside and out.
Goes without saying, right? Maybe, but I hear storytellers sometimes who have not done this step.
Try to imagine every character, every setting, every action completely. When you do this, you will be able to answer any question that comes up about the story. What color shoelaces does the heroine have? How old is the big brother? How does the cat cross the room? You don't need to put these in the story--in fact, if you did, the listeners may keel over from boredom--but you do need to know them. When you imagine the story that deeply, your choices about what images you use will be clearer. Hmm, is that true? Sometimes I make these pronouncements and only later do I wonder if it works for everybody.
I'm a visual learner. I see the pictures of the story in my head, almost like a movie. I translate those pictures through my heart and bring them out in my words, voice, body and face. More on that later.