Students may be noticing more about you than you realize. They want to see if you are sincere. They want to see if you can be trusted. They want to see if you care.
Believe it or not, many students notice the amount of eye contact that you give them.
Poor eye contact shows that you have something to hide or that you aren't confident. Even if these things may not actually be true, they are not what you want to be projecting to your students.
Be confident. Make good eye contact. Let your class know that you aren't scared.
Own your classroom.
Your students will be the ones who benefit.