Though it goes against the ideology of a lot guys, I usually only ever give my number, rather than taking theirs.
There is serious psychology and reverse psychology at play here, as this is likely the first time either one of you has clamped eyes on each other.
The predominant factor for consideration is INVESTMENT, both proactive and reactive.
The provision of a phone number is a reactive investment (to the situation, and one that you do not and should not care for the result of at this point). The taking and using of a phone number is an active investment, one that requires a prerequisite level of interest.
If you text/call (though I never call women) the next day, having taken her number, she will be immediately reacting to you passively, while you are already actively investing (by taking time to get her attention, trying to meet etc.). Where my personal view is that upon first meeting, you want to gauge her interest level, before you start investing time texting and trying to meet her again.
You want them to be actively investing at the earliest opportunity. By giving them the opportunity to get in touch first, you are forcing the active investment in to their court.
What many DJs fail to (consciously) acknowledge by never giving their number out and only taking numbers, is that they are already investing in and flagging their level of interest to a girl by texting and calling first; apparently the cardinal sign of a beta male.
I don't care if a girl texts me the next day or not because at that point I have barely invested any time or effort in her. If she doesn't then I obviously didn't work hard enough on first engagement, or she simply isn't interested; in which case the boat is likely sailed and I have not wasted energy on her. If she does, I know the game is already on.
I would say 99 times out of 100, the girl has got in contact after me giving my number. I have had less success by taking numbers myself.