If I'm nervous about something and if I'm in public, I tend to always fondle with the hair at the nape of my head, and if I'm at home and nervous about something, I'll walk to the front door and shake the knob to make sure it's locked. I try to stop myself, but they just seem hard to break :-/
Oh, and if I'm talking to someone I'm really shy around, I won't look them directly in the face and I'll keep wiping my eye nervously. It's embarrassing