they say the person who cares the least has the most power
I have found if you txt her too often she won't be so interested, is bizzare so
after getting her number i usually wait a few days before txting her/calling her
if you set it up right women will enjoy anticipation

then match her level of responsiveness but occasionally deliberately leave it longer to reply.
if you met and corresponded on the internet, and have not met in rl yet txt is fine
if you can talk to her at night on the phone, thats great too!
just keep it playful and short.