You can't catch me, I'm the gingerbread man. I know how I'm going to begin and end the story because the beginning and ending are very easy to get tangled. Your audience senses if the story is alive for you. If it is, it will be for them too. It is important to discover your own style of telling, not to imitate someone else's.
Some fine tellers are very quiet, others are highly dramatic.
Some use different voices for their characters, others only change their tone. If you feel very nervous, rely on your carefully considered beginning to get you underway. By the time you get to the body of the story, your pleasure in the story and your audience's pleasure will probably take over and carry you to the end. If you suddenly can't remember what comes next, remember that you have spent a lot of time inside your story, making it something like a memory to be recounted. Drop back into that inner memory, find your place and you will be able to go on.