Firstly, she have to give you signs that she "might" actually like you romantically. Otherwise just bring her clubbing and make sure you bring more of "your" friends than she has hers. Make her drink a lot, then bring her to your room. Wake up in the morning and pretend that you were also drunk and didn't know what happened. There's the "WILD" and "ADVENTURE" for you.

Otherwise, if she knows you well enough then bring her for a vacation. Something like a beach vacation with plenty of activities like banana boat rides (can drag her down from the boat) or jetski (ask her to drive the boat while you hold her from behind). Body contact is important for her to develop possible romantic feelings. And good food is important. Once she has a good imprint of associating you with fun, then it's easier to proceed to get her to lay in the same bed, preferably not doing any sleeping or talking.

IF she's not close to you, then you better have a sparkling personality and knows a lot of happening spots and events that she might be into. Say if her "playful" side also means SM, then you better know where to get your leather and whips gear, and SM events. You'd also better have a car, girls always prefer guys to drive, even if they have their own car.

If all else fails and you're a very desperate prick, then stick to the "OMG, how the hell did this happen? It seems that we got drunk and slept with each other..." Feign innocence, it works.