Fake it till you make it.
If you know , you will be in a situation which makes you feel nervous / uncomfortable. Be ready to bring out the actor in you.
Pretend that you are the most confident person , smile & stand tall. Look people in the eye , ensure that your handshake is firm and use a few well rehearsed lines.
Once the ice is broken and the first impression has been set , you will find it easier to manage the rest of the event.