(Disclaimer: not all of these I agree with.)

• Talking to yourself
• Biting fingernails
• Unconscious pen clicking
• Cracking your knuckles
• Lick or bite lips
• Humming to yourself
• Biting your pen/pencil
• Twirl and pull hair
• Grinding teeth
• Rushed speech
• Tapping your foot
• Touching your face
• Fiddling with keys