Increasing Confidence

One way to increase confidence, is by increasing perceptions of control. Here are a few things (this is far from an exhaustive list) that you can control in almost any situation:

1, Your breathing: Take a moment to stop, and take control of your breathing. 
2. Your attention: Choose what you want to focus on, preferably something that will be helpful in this situation.
3. Your posture: Lift your head up, act confident. Fake it till you make it! 

Related to posture, here is a fantastic video on the topic:
Amy Cuddy- Power Poses