Going to a swingers party with the aim of having one-on-one sex with a single woman kinda defeats the whole purpose of going to a swingers party doesn't it? I'm sure a lot of 'swingles' will beg to differ but nonetheless I'd suggest that you open your already open mind a little further to make the most out of your night out.
I think your experience will depend on the type of swingers club/party you decide to attend. Some clubs have theme nights specifically catering to single women and females of couples who enjoy a lot of male attention. That being the case, you may well get your chance to play with a single lady but don't be surprised if she wants other male company in the room. Some ladies may prefer one-on-one fun with a few guys during the course of the night but you'd have to play that one by ear unless you want to interrogate all the girls about their preferences.
As for couples, some ladies do seek out single guys for one-on-one fun at swingers parties but again, you'd need to be open to having her partner watch or join in occasionally, if that's their 'thing'.
Most clubs and parties limit the number of single males that can attend so the ratio of men to women is reasonable though more in the ladies' favour for good reason (some girls are just plain greedy). Having said that, if you're an arrogant, pushy tosser then it wouldn't matter if there were 20 girls to every guy so make sure you're the sort of guy the girls feel comfortable around.
Ensure you're nicely dressed, cleanly shaven and polite to everyone at the party. Be open to talk to everyone there and don't be surprised if the male partner of a couple approaches you to do naughty things to his wife.
As I mentioned, keep your mind open and do remember you're at a swingers party. Think about how you'd feel if a single lady indicates her interest in you but later suggests she'd like one or two other guys to join in. You need some flexibility in terms of what you would/wouldn't do play-wise to increase your chances of having fun. On the other hand, if you're sure that you only want one-on-one fun with a single girl, you may be best to search on RHP to make your own party for two.