Not helpful: Having strict, limiting criteria
By all means, we should aspire to meet amazing girls and guys. But seriously, if you have non-subjective criteria that say things like "must have a master's degree" or "must go to the gym five times a week," you're not helping yourself. Having a master's degree doesn't guarantee a person is smart, if being smart is part of your criteria. Similarly, finding someone who cares about his or her health doesn't necessitate gym membership.
Helpful: Asking close friends to set you up with people they know
If you have good friends who really get and understand you, certainly they have some sort of idea who you'll get along with. Ask them to introduce you to people. The risk is low, and the upside is super high.
I've dated guys my friends introduced me to, sure. Some of them turned out to have issues (either anger management or extreme unhappiness), but I learned a lot from those relationships, too.
I just wish my friends would do a better job, haha kidding. But not kidding.
Helpful: Learning about feminine and masculine energies
Everyone, single or not, should read David Deida's book Intimate Communion. It very clearly lays out what feminine and masculine energies are and how they work in our day-to-day lives. It will open your mind to understanding your partner or others in your life/work/dating. Questions like, why don't men want to commit? Why do working, professional women exude masculine energies and therefore also lose their femininity outside of work? Why do we date wimpy men? What are the differences between love, romance, and sexual polarity? How come we're attracted to the same kinds of guys all the time? Why do we have these patterns?