The key is being fit and having variety IMO. Women don't know what they want... end of story.
For guys, being fit is #1 far and away. It's not optional, it's a requirement for good sex. It means you'll have more confidence as well as turning the woman on more. That physical health lets you get into more positions, have more stamina, and have harder erections (also, have 0-2 drinks before sex... not ten).
As for technique, guys just need to know anatomy... namely cl1t, gspot, and other sensitive areas (back on neck, nape of neck, back of knees, inside of thighs, small of back, hip bones, wrists, etc). You need to know all the basic positions, especially the ones that are good for her (woman on top, reverse cowgirl, and doggystyle for most women). You need to know how to give good massages and good oral to the woman.
Perhaps most of all, you need to know how to flirt and how to kiss... or you won't get much further. Flirting goes a lot further than compliments... you need role play, costumes or sexy outfits, mind games, occasional BDSM situations, etc etc based on the woman's comfort level and sexual openness.
The VARIETY is key because women are in different moods at different times. Sure, most guys would like it porn style... fast an heavy 99% of the time, but women aren't like that at all. Sometimes they want to be loved slow and passionate, sometimes they want to be railroaded and ravaged, and usually they want something inbetween. I've had girls tell me I need to stop treating them like a porn star in bed, and I've had others tell me I need to be more assertive and "more of a man." It all depends on their mood.
Lastly, you need experience. I guess that could come with one or just a few partners, but generally, I think that guys who care about being a good lover and have been with a variety of partners will just know more tricks. You pick up techniques and advice from each lover... assuming you pay attention. GL