Kind of paradoxically, men are very open minded or very even handed with their votes of women.

Women are much more discriminating. I think both types of people are equally interested in having an attractive partner. But women essentially give the thumbs up to only half as many guys as guys giving the thumbs up to women.

You take a picture of yourself in some exceptional situation - skydiving or whatever. People always post those photos because it works - you're saying something about yourself that begs a conversation and that's what the users are there for.

Use correct grammar and punctuation. Do not use net speak, like WOT, W-O-T or U. Those messages get a lot lower reply rate.

Going to a site with more users seems obviously better to me, but at the same time, having a bland, middle of the road profile with bland, middle of the road pictures seems like a bad strategy to me.

Even at the person-to-person level, to be universally liked is to be relatively ignored. To be disliked by some is to be loved all the more by others. And, specifically, a woman’s overall sex appeal is enhanced when some men find her ugly.

A great piece of advice for online dating is to stand out from the crowd. So greetings like "hello" and "hi" are very common. They do less well than things that are a little bit quirky or a little bit weird, like "howdy" or "holla." The rarer your salutation, the better it does, in general.