First be comfortable with it, introvert and proud. Be comfortable Not talking to people,its ok. If you are at some gathering learn to be completely comfy sitting alone and chillin. No one there is more important than you, so who cares what they think. People are drawn to people who are comfortable with themselves even if not outgoing.
Be quick to smile and look people in the eye.
Practice by simply giving someone a compliment (that you mean). "nice tie" "I dig your hair" whatever.
I find large gatherings tedious and people draining but oddly at this point I am really well received, mostly because "I dont care" and a smile goes a long way.