#nailbiting

How do I help my tween son channel/ work through his emotions in the healthiest way possible?

I have a question about my tween and anxiety. I have noticed that my son bites his nails and fidgets with something in his hand, and now I’ve noticed he bites the side of his mouth. I think it is increased anxiety from an increase in school work/ expectations/ longer days in school.
What is the best course of action to take?