Adam Carolla has often mentioned an interesting observation regarding women. The nervous looser creepy guy in the workplace cannot get away with anything. If he even looks at a woman or comments that she has a nice shirt, she will report him to human resources for sexual harassment. In contrast, the coolest guy in the office can get away with saying anything he wants. He could walk in and comment that it looks like she got laid over the weekend while slapping her on the ass, and she will just laugh and like him even more. What you say matters much less than how you are perceived by your peers. Women cannot help but be attracted to men with a higher social status. Instead of always worrying about what lines to say, become the cool guy in the office.
Take some time to make sure you like yourself. Do you consider yourself a good friend, a funny person, or just someone cool to hang around? If you do, who loses if you don’t get to know someone? They do. So do them a favor and get to know them better. You are not putting yourself at risk for rejection. If a woman rejects you, it is her that loses, and as trite as it sounds, a woman cannot reject you, she can only reject your approach. She doesn't know you enough to reject you, and your approach is easy to change.
If you are the most awesome guy in the world, you don't need any lines or techniques, but I'll share a couple anyway.
Treat her like a bratty little sister. Assume you can do no wrong. If you screw something up, laugh at it, don’t get flustered or overly apologetic. Just don’t overly tease women with low self esteem or a shy personality.
Swat her with something small like a straw or newspaper, and only when there is a reason to.
Don’t give her your full attention. It shows you are too invested in the outcome. Start conversations and don’t be afraid to walk away and come back later.
Anytime you hang out with a woman, she will probably make a minor error or faux pas. Complain about her mistake in a far too serious way. Bring it back up multiple times like it is the most serious thing ever, obviously joking(or are you?). Remind her how she just ruined her chances with you.
Pretend you are the super attractive woman and she is just another pussy guy seeking your approval. Misinterpret everything she says this way.
Comment on her subtle body language cues in a teasing way. Women are used to noticing these minor details, so commenting on them yourself shows you understand. Interpret them all as interest in yourself.
Treat any emotional outburst (which is probably a test) as cute. Cute enough to be kinda funny. Many times women test men this way subconsciously to see if he can keep his composure, or if he will turn into a wussy guy. Other times it isn't even subconscious. Don't fail these tests.
Start questions with “On a scale of 1 to 10", you will find out much more about her.