How to Mingle:

Always enter a conversations with a drink you are about to finish.  If things don't go well, all you need to do is take one last gulp from your drink and excuse yourself to get another, never to return.  If the conversation is going well, finish your drink and ask the other person if you can get them anything when you go to get another. They will appreciate the gesture even if they decline, and it impies that you'll be returning for a longer conversation.