The way I counter my shyness is to learn what would be appropriate should a mishap occur. Such as, what do you if you stutter or god forbid, trip.
Try to act out scenarios with friends and family that you may do at meetings and other more formal get togethers. Sure you may laugh, but you'll develop 'muscle memory' of the motions you go through in such an event.
Practice, practice, practice in front of a mirror... no matter how silly you'll feel. It's important to know what kind of facial expressions you're conveying... and how to will the ones you want. This will give you a much needed sense of control --- if you don't feel confident, at least you know you look confident.
Learn how to focus on one person at a time... instead of a whole group. Remember, it's easier trying to talk one on one... so have that frame of mind.
There are other tricks... but these are the ones that readily come to mind.
"The weakest soul, knowing its own weakness, and believing this truth that strength can only be developed by effort and practice, will, thus believing, at once begin to exert itself, and, adding effort to effort, patience to patience, and strength to strength, will never cease to develop, and will at last grow divinely strong."
- James Allen