Basically you're going to have to take a risk. Just bite your lip, take a breath and go for the kiss. Either she kisses you back or she doesn't, and from there you'll know if you did well or not.
But if you're looking for a routine, try one I got from Style. Look her in the eye and say "Do you want to kiss me?"
She'll say one of three things...
No - You respond "I didn't say you could. You just looked like you had something on your mind."
Yes - She'll rarely say this, but if she does, kiss her.
Maybe - This is the most likely response. You then say "Well let's find out" and you kiss her.
The other one I learned from Adam Lyons last night.
Somewhere in the conversation, either when you get her a drink or when you're talking about something cool, give her a high five, and pull her in for a hug. Just a hug. This way she gets used to hugging you.
The next time you get to that point, hug her again, but this time kiss her on the cheek.
The third time you do it, kiss her on the cheek, and then pull away but keep your hands together. Immediately go in for a second kiss, aiming for her mouth. About halfway through, change direction for the second cheek instead. Pay attention to what she does here. If she automatically gave you the second cheek, she's not looking for a kiss. If you have to work around her to get to the cheek, she was expecting a kiss. If she does this, pull out again, and then go back in for a third kiss, this one finally on the mouth.