Quick destroyer for the infamous,

hb: "I don't like to give out my number"
me: "neither do I that is why I asked for yours"
hb: "what now?"
me: show me yours **pause** bbm pin --e-mail or SPAM if they don’t use bb—( i strongly advise anyone to have BBM)

Have fun out here!

that produces a flaky number I think.

Also I don't ask for numbers.
You should make some future pacing and then put your phone in her hand, say; 'Just type in your digits and I'll send you the info' or whatever
I think Alex Coulson does it this way. Actually I just translated what I say in German
So what this does is, it takes a lot of pressure. Cause she won't have to do anything but read a sms and not answer the phone. Also you leave out the key-word 'number' and the question. She has no time to think about it when your phone is in her hand right?^^
My experiences doing it this way are 100% positive. And you can also call her then...usually I text them something funny later the same night.

And if she rejects you first when you ask her for her number and you still get it you could also just go on and build more attraction and comfort in order to disflake the number

I keep reading things about putting your phone in her hand...

But what happens when she looks at your hand with your phone in it, and says: "I dont give out my number" (or something)??

You got a (little) vibe going with her and she leaves your hand hanging...?
(While she might be playing with you)

Just say, I understand, there's a lot of creeps out there. Then continue talking, build more comfort, and ask again later.

Also, I don't like 'asking' for numbers, you should make a statement. "Give me your number so we can hang out again some time", "Yeah it's a really cool place, lemme get your number and I'll take you there some time."
Something like that.