Something I found quite fun and flirty was to talk in 3rd party for your first text back to a girl and to label each other. For example if you remember something about the girl that sticks out or you teased her for you can start with
Wig Girl wanted to party all night with Intoxicated John.
It can start getting into a roleplay type thing which girls always love just remember to refer back to it every now and then and it will get a giggle
try it ::)