Great question and this is always a challenge when it comes to meeting recruiters face-to-face and making your best impression. Remember, you never get a second chance to make a first impression. So how do you effectively demonstrate yourself and "stand out from the crowd"? I think the first step is simple, starting with dressing professionally and having confidence in yourself. But secondly, depending on the type of event you will be attending, I would prepare an "elevator speech" of some kind: this is your 20 to 30-second opportunity to show your recruiter who you are, why you are interested in what they are recruiting for, and why you think you fit the position (if this is for a job opportunity).
One piece of advice I would add to this is to be natural. Don't worry about memorizing a speech or being overly impressionable. Go in with a firm handshake, be yourself, and show the recruiter why you have the passion and drive for the position you're aiming for. Best of luck!