I'm an occasionally lurking female and have the same problem (with men). It's not really that you're picky. There are a lot of good women (and men, in my case) around, but most of them are in long-term relationships, and, when you find out someone's in one, you generally don't even consider them. Nor is it that you're less picky than most people on this board: it'll take someone special before most people here will "settle down". In the meantime, though, many of them will quite happily settle for "less". It's just that they enjoy "less" more than you do.
How does one get more out of "less"? Three ideas I've had:
1. Act quickly. I've met some men I've felt an instant mutual affinity with, but, if I bother to talk to them for a few hours, it usually goes away. Now I kiss them first (providing the context is suitable), chat second and bid them farewell if and when the magic wears off. It's not a solution, but it makes life slightly more fun.
2. Scenario: Someone you like, but have no particular chemistry with, asks you on a date. Do you agree?
Of course! Ok, it probably won't go anywhere, but it'll be a bit of a change and a bit of a challenge. No harm done and you never know what might come of it.
So, if you wouldn't say no to them, you should ask them out yourself. Yes?
3. Being more "peoply" and random seems to help. Until recently, I was only attracted to men with certain features and interests, but I started socialising outside my normal circles, going to different places and agreeing to weird suggestions, and all of them made me more attracted to men I wouldn't have previously considered.
As to grad school, it hasn't worked for me in that regard thus far, but it is good for meeting intelligent easy-to-talk-to people, and half the people in my department seem to be going out with each other so there might be something in it...