Dude, you don't need time and effort. All you need to a look in your eyes that doesn't scream "goofball." If a girl thinks that you don't care about her or anyone/anything else, she wants to put your dick in her mouth as if her life will be depending on it. Don't ask me how that makes sense, because it doesn't. But what it is - is absolutely true. If you can just be cool, aloof, light and breezy, you'll find that you're able to bang any snatch you telepathically will to you, or damn near to it.
I actually put this to a kid who was in line for GTA4 last night, and he didn't believe me. So, I asked for the woman's opinion (my Asst. Manager's GF dressed up as Lola - the lollipop girl from the GTA cover art) on whether my system was actually viable or not.
She said that it was absolutely true - an overabundance of balls is far more attractive than no balls at all. You're shy, you die, and it's that simple. And to that whole idea of having a look in your eyes that's 1/2 playful, 1/2 total ambivalence...well, she told me how well that works, but I won't say it verbatim on here (there are folks who may know these people on here, and I don't want to get anyone in any trouble over misconstrued bullshit). Let's just say that it's failsafe and foolproof, and if you don't believe me - you must be a fucking virgin, man.
I told you once, twice, too many times to count:
If you need a guaranteed strategy to get laid, just ask your boy. I know the secrets of how to make the vag come to you, my sons.