I would wear something that clearly identifies me as a personal trainer. I have a few shirts with my name and the name of my company embroidered on it which I always use when I attend functions like that. I also have a lot of business cards on me and a brochure about my business.
Once at the event, I talk to everyone there whether they be potential clients or other business owners.
I wish you good luck and success.
If it’s something that you can promote your services, I would have brochures, business card, flyers, or anything that you can give to potential clients.
I would hold some type of testing that can be used for a big population, maybe Biolelectrial Impedance Analysis-Body Composition (not accurate but good for big populations). Maybe an “Ask the Personal Trainer” session, allowing them to communicate with you. You can also hold an exercise demo of some sort, TRX, BOSU, 5 Minute Core/Ab session, etc.