Use the situation that already connects you. Ask for a small recommendation, comment on the event, make a light observation, ask how he knows the host, request an opinion or offer a sincere compliment about a choice rather than his body.
Examples work best when they are specific: “Have you tried the signature drink?” or “What did you think of the speaker?” gives him something easy to answer.
Prepare, then stay flexible
Have two openings in mind before you arrive. Once he answers, stop following a script and become curious about the person in front of you.