It is absolutely normal to be a bit anxious when we have an event of some kind coming up. It gives us energy and help us to focus but if we are too anxious we can feel overwhelmed. 

Our unconscious mind naturally sorts for what we focus on so the more we focus on things going wrong the more likely it is that will happen. Instead imagine the event turning out really well. Picture it, seeing it as if it is a video playing on a screen.  What will you see, hear, feel?  Imagine yourself stepping into the picture. How does it feel to have things turn out like this.  Adjust the experience till it feels just right then journey back to the present noticing what has to happen to achieve this. 

It can help if you write the outcome and all the steps down.

We naturally focus on an event coming up if it is one we want to go well so we might as well focus on the outcome that we want.