First Tee nerves tend to hit most people. You want to get off to a good start, you don’t want to do something to embarrass yourself and you feel it is a positive way to get things going.
There are a couple of good things you can do. First try and work on your breathing, slow deep breaths. You want to try and slow things down and do your best to try and relax.
The second thing you can do is try visualization. Most people tend to play the same course or same courses. You also tend to have favorite holes, ones that you tend to play well and you usually hit good Tee shots. As you are standing on the first tee visualize that you are playing your favorite hole. Picture the quality shots that you have hit on that hole and then try and duplicate that on your current tee shot.