Scared to tryout for sports?

I currently just finished 8th grade and im starting high school in the fall. I really want to tryout for volleyball in the fall and i also want to try out for tennis in the spring. I have a feeling I would make it because I am tall and have potential, but I've never played either of those sports. I'm so scared to tryout, I dont know why. I think it might be because I won't make out or because I'm just scared to play in front of people if i do make it. Help please?