I just read a very interesting and well-written MyTake by DexWest on dating and it inspired me to put down some of my own observations to add what he's started in this take: Observations on Behavior in Dating: A Battle Between the Sexes
I would say that two fundamental mistakes I see inherent in all of the whining you see from guys about girls in the dating scene and from girls about guys in the dating scene are these: 1) Dating IS a competitive game but it is absolutely NOT a competitive game where the teams are "guys" and "girls." In dating a guy has competition from OTHER GUYS and a girl has competition from OTHER GIRLS. 2) It's helpful to further segment the groups into "desirable (guys/girls)" "average" and "undesirable." I typically see the whining guy posts fail to make this distinction when they say nonsensical things along the lines of "girls have WAY more sex than guys do! It's not fair!" Yeah--it's also not POSSIBLE since EVERY time a girl is having (hetero) sex, there's a hard penis involved and there's a happy guy at the other end of it. The reason this segmentation is helpful is it highlights exactly what's going on. We tend to focus ONLY on the "desirable" sub-segment of the opposite sex and ignore the rest. And more often than not, if we're complaining about our outcomes it probably means we are in the "average" or "undesirable" segment of our own sex. So the FIRST thing to do is to work on moving up the desirability scale in our own sex. That takes WORK but it CAN be done (ESPECIALLY for guys, but for girls too).
If I were to add a third fundamental mistake I see being made it's that attraction, dating, and relationships are all a PROCESS where things TEND to need to happen in a certain ORDER. That is, you need to generate SEXUAL attraction from the person you'd like to be with FIRST, only THEN does it do you any good to demonstrate your "good relationship material" qualities. You see the failure to recognize this reality in even the Psychology Today articles cited in the previous MyTake. I'd hazard guess that 90+% of the time someone ends up in the "friendzone" it's because they've spent all kinds of time and effort to showcase their "relationship material" qualities and they've failed utterly (often not even TRYING) to demonstrate their sexual desirability.
Anyway, those are some of my thoughts. I'd be interested in hearing if you see the same thing or something different.