First, kudos to you for being brave enough to consider going on your own. Many don’t even get that far.
My first party was a Christmas-themed fetish night at a local lifestyle club. I did go with someone, however, there are many who go alone. The atmosphere was fairly casual and welcoming, so try not to be nervous.
I don’t know if you’ll have time for this before your party, but hopefully, this is just the first of many others you attend. I’m going to assume you saw the event on another fetish site. You should be able to see the other RSVPs… read their profiles and follow the ones you’re interested in meeting, not just for future play, but as potential lifestyle friends. They may recognize you when they see you there and come introduce themselves. Or vice versa. Go into it with no expectations except to get a feel for the venue and the local scene.
From a wardrobe perspective, most start with vanilla-appropriate clothes and change once they get in. Many women bring lingerie to change into a little later. Most of the clubs/events I’ve attended are very body inclusive. I usually wear jeans in the door and change into a very tight dress and heels once I get in. You can’t go wrong with a black dress, fishnets, and heels. Sometimes I change into lingerie, sometimes I don’t. I usually strip to my panties for scenes, so I like to keep it simple and easy sometimes. If you plan on changing, don’t forget to bring a lock… preferably combination (you don’t want to have to find a place to keep a key).
I would also recommend attending munches, sloshes and meet and greets. They’re more casual and low key, and a great way to meet and vet potential play partners. Many lifestyle clubs have meet and greets on Wednesdays or Thursdays.
Once you starting getting out and meeting people, it’ll develop further organically. I go to clubs and events by myself all the time because I know enough people now that I always have someone to chat with there. And my tight dresses and fishnets lure in the rest.