hey steve when you get dead numbers and girls ask who's this?, that is a bad sign, same thing with girls that always have excuses for meeting up with you but if you ever want to try to revive dead numbers and you get a who's this, some personal favorites are
prince charming,
the man of your dreams,
guess who it is, if you do, you win something...
(consider who's this as her trying to shit test you, with a hoop, don't jump through that hoop, makes you look like someone unimportant, it is still fairly unimportant, but if she is going to tool you with, hurr hurr I donno who you are/removed your number, then you should tool her back)
the opener doesn't matter too much, something open ended and ambiguous will grab attention better, but to check interest/mood it is probably easier to use something closed that doesn't require an answer, and then of coarse there is always just a regular greeting
*eg. of open ambiguous*,
whoaaa you are not going to believe this!!

you will never guess what happened today :O
*eg. of closed interest checkers*
YEP, IM FUCKING AWESOME

CONGRATULATIONS!!
wow gum sure is chewy
I like pie
Holy shit, slugs have four noses, that's crazy!!
*eg. of regular greetings*
Hey, whats up?
yooooooooo, how are you?
Are you still alive?, been a while!!
hey
hi
sup
yo
holla
shallom
bonjour
allo?
bounjourno
go ni chi wa, bia bia!!
neeee how!
there is also a list of cheesy/funny openers somewhere in the routines section, with a crap ton of openers, you don't really have to be too amazing, to be honest you want to tone it down a bit here and there, girls expect congruence if you are congruently always trying to cause emotional spikes they will come to expect it, you become their entertainer, and when you can't deliver they will lose interest, make sure you are balancing awesomeness with normal boringness, don't try too hard, let her invest for the awesomeness instead of just giving it all the time 24/7