I don't think you should be embarrassed of your smile. I mean, don't smile too much obviously lol. Just do what I do and smile a little but don't exagerrate it.
Tbh, even though I'm not into plays, I wish our school had plays to see how much people in our school suck at acting. I can tell who would joinng if they had one, and there are plenty people in my school who I know have bad acting.