I used online dating off and on for a little over a year in the mid-2000's and eventually met my future wife. To be sure it was the combination of persistence, time, and a little luck. I was tired of trying to meet people in the same old cliche spots. I used match.com back in those days, and could set my profile to what kind of relationship you were looking for so it was easy to filter through candidates.
Of course now there are a ton of sites available for options, so it depends what you're looking for. Having said that, I take it you just want some action? Typically the sites where people are looking for stable relationships will have higher quality females. Things like adultfriendfinder.com (if that's still around) are a giant waste of time IMO because hot women don't need dating websites to get laid, resulting in a site that's nothing more than an online sausage party.
Have you already tried the usual spots (bars, clubs, the produce aisle, bus station bathrooms)?