Don't be that touchy-feely creep guy who hugs without asking or takes stuff without asking either. I encountered such a creature a couple weeks ago who just took my fursuit head and paraded around with it without asking me first. If there's fursuiters there, approach so they can see you and ask for a hug first, don't just assume because they're fluffy they want ALL the hugs.
Bring a sketchbook if you draw or a 3DS if you have one, you're bound to find somebody to Spotpass or ArtJam with.
And it goes without saying but...you're in a restaurant so be kind to the waitstaff, be considerate of other people around you (who may or may not be families with kids), and if you order anything, pay for it. I help run a large three-state fur group on Facebook and we constantly have to remind people to bring money for meets because people will just leave without paying. You want to be able to go back to these places, pay your bill and tip too.