Best Pickup Line ever: "You'll do."
My favorite one that worked almost every single time for me back when I was in school is this... On my way to class, I'd come up to a random girl I liked (had some that I had class together but never got a chance to talk, etc) and:
I: "Excuse me, do you have a pen I can borrow for a moment?"
Her: Looking in a purse, getting one out and giving it to me...
I: "Opps, sorry, but would you also have a piece of paper?"
Her: "Sure, bla bla" Looking in a purse to get a sheet of paper.
Usually they like to get a bit comfortable to pull a sheet out and move if there is a table close by. At this point you already "got" her into the "conversation and forget about everything else for a brief moment" mode as you have her pen that she waits for. You can start a slow conversation while she is looking for a paper, school is an easy place to start with generic question like - wow, thats a lot of books, what are you studying? bla bla, how do you like it, how do you like the school, etc...
She gives out a piece of paper.
Here is where it gets important. At this point you take a pen and a piece of paper that she gave you, and give it back to her - "Hey, I just think you are gorgeous and wanted to get your phone number, can you please write it down for me?"
Or something along those lines...
At this point she already feels like she did so much and providing a phone number is not a big deal. Most smile to you and you can continue the conversation, some give the number and leave, just say talk to you later, some say they have a boyfriend or some other excuse, but this pickup line was one of the best for me.
Once again, apply affiliate marketing thinking. page 1 - just hey, click here to blabla, page 2 - throw the benefits, relate, talk, get some action back, page 3 - get email address (phone number).
Now that was an easy part. If you are an affiliate - you got a lead but here you got a lead for your own product and need to follow up and close the deal, which is harder. I had girls that never picked up my calls, had one saying that she was not interested in dating and not to call her back, etc. Its your call, but if you get a lot of leads, it doesn't really matter since you need to close just one (or a few), unless of course you all of the sudden want just one particular one.
And, depending on the case, use other lines. Like when I was just walking close to the club with friends and a couple girls walking my way, "Hey girls, wanna go party?" may work just fine too since they are in the area. Its a different type of traffic, like ppv - you just throw your pop up and see if it works.
Pick up lines are not the problem, the problem most of the time is that you are just scared to come up to the girl and tell her what you want. Sometimes you have no idea how to start a conversation, and "Hey, do you have a pen?" usually works as the girl doesn't even feel like you are hitting on her. Just a generic question.
Meanwhile, you also get a moment to observe and notice an engagement ring for example. Then just ask for a piece of paper as usual, if you are already talking to her at this stage, can just congratulate her on upcoming marriage or something to make sure she is engaged, etc... If you decide to pass on, write something stupid on the paper, give the pen back, thank her and leave.
tl;dr: Ask a girl for a pen, ask for a paper, give it back to her, ask her to write her phone number, get it, feel like a boss...