Attending a ½ day seminar, or an evening networking event-with-a-speaker is a chance to make new contacts.
When everyone seems to be engaged in chatting to everyone else (there are diagrams that show open and closed groups), look for the person sitting alone.
Chances are strong that they are shyer than you - that's why they are sitting alone and you are actively considering approaching them.
(Remember: to a three-year old child, a five-year old is an expert).
If no one is alone, then gravitate to the door and greet the next person that walks in.
You'll catch them off guard, and if nothing else they'll assume you are a "greeter" and they'll start to chat with you.