What is the common theme that is bringing you all together? You'd have to be familiar with someone or some aspect of it, or I'd guess you wouldn't be there; how did you get invited? If there are going to be guest speaker(s), strike up a conversation about them. Mention your familiarity (or lack of) with the speaker, or the subject matter. By your avatar I presume you're a woman; make a comment about a guy (or woman if that's your persuasion), or compliment someones clothes (no catty remarks allowed here). If you're concerned about conversations with someone you're attracted to, well how hard can that be? If the event is outside, as trite as it may be, mention the weather, and how it may effect the event. Mention the scenery/location. Is it a particularly scenic area, or if it's in the city, talk about the landscaping if it's well done. Will there be live music? Is it your style or not? Will food be served, and how--buffet tables, catered, pizza delivery? Make comparisons between this event and another you've been to, or just a similar situation. Find someone who is the life of the party, walk up to them, introduce yourself and ask how they do it. Tell them you're usually a little on the shy side and would love to learn to mingle better. Guess what? You just did!