Hi! I've read your post about N-closing and hopefully I am able to add some value.
Where do you experience the problems: are your numbers flaking, doesn't she want to give you her number or is it an inner game thing (you're uncomfortable asking for a number)?
First of I am not an expert, but I might give you some ideas to try out and see if it works for you.
It's already said in the previous post but I aslo found that my so called "flake-rate" went down when I used an reason to ask for a number. I've really come up with the most stupid reasons. For instance: steer the conversation to bars/clubs in the area and invite her to come with you. Open her by asking where she bought her handbag because you would like to by a gift for your sister and N-close by telling her that you could let her know which bag you've bought, etc.
Short (kinda stupid) example of how to steer the conversation:
HB: I live in Amsterdam
DS: No way, some of my best friends live in Amsterdam. Which bars do you like the most?
HB: yadada-bar
DS: I've been there as well. Next time when I am in Amsterdam we should meet. OR Never been there, I've been in the bladibla-bar. But next time when I'am in Amsterdam I am gonna check it out. What's the best way of staying in touch because then I can let you know when I am around.
If she doesn't want to give you her number:
I have seen AFC Adam do some things.
Say: "What's the best way of staying in touch". She replies with "facebook". You tell her: "Ok nice" and start typing her facebook in your phone. Then say: "damn, all that typing isn't easy. You are giving me trouble already. What's your number, because that's easier".
I've also noticed that when she hesitates to give her number it helps when I say: "It's oke, you can also give me a false one". I think it works because it releases the awkward pressure.
If it's an inner game problem, the only real thing that helps in my opinion is pushing through your comfort zone. But it might help to start small.
Another thing I've read from AFC Adam. I tried it and in my opinion it's golden! Use the following as opener:
"Excuse me, I have a kinda extraordinary question. I just dropped my phone and I expect an important call but I don't know if my phone is still working. I am afraid that it doesn't receive the signal anymore. Do you mind calling my number to see if it's still working." Then add: "Don't worry, I wont pick up the phone".
When you've done this her number is already in your phone. When you continue talking to her you don't have to explicitly ask for her number because you already have it! Hope this helps.

If you have any question: feel free to ask!
Dutch Student[/i]