from experience i'll say what i would do. i've had three ex girlfriends BEFORE i got into the game and each of them sucked money out of my pocket. the key is to NOT let it become a habit. other PUAs might say you should never pay for things until after they have sex with you, but sometimes it doesn't really matter that much. girls do like it, the more insecure they are... the more they'll appreciate it.
there's two ways i would do it. one way, i would play at extremely smooth as if i was a big shot. make it literally look like nothing, just keep talking as you pay for whatever it is, keep the conversation OFF money and stuff like that for a while... especially as you pay. don't go off into the "are you paying? are you sure? i'll pay next time?" etc...
if you do it correctly, it'll be huge DHV. i know girls who told me things like: "i love it when a guy leaves to take care of the check, that way when we're immediately done with our food we can leave instantly..... and on to my place

"
and the key is to act like it's nothing and say that when she says thank you. just say "don't worry about it" and change the subject completely. off the restaurant, off how the food was, off money, or who owes what, etc.. act interested in her in PUA. give her IOIs when she does. play it cocky/funny, alpha, throw negs still. so yea...
that's one way. i still do this and i've found it extremely affect. they sometimes fall in love with you, but maybe that's just the whole package of playing things smooth. the second way is the way i would do it if they absolutely cannot pay at that moment. basically just say something like:
PUA: wow, no money huh? don't worry i got it this time. but you owe me big time.... and i'm not talking cash, i'm talking some sexual favors *laugh*
HB: ewww, no! *playful hit* (IOI)
PUA: yea, and i'm not talking about the romantic stuff, i mean the hardcore, raw, aggressive stuff. i love that! *smile/laugh*
HB: haha you're a typical guy (shit test)
(pass the shit test and you're in)
something like that. or maybe she'll play along and be like "ok how do you want it". those are the tricky ones. it's more obvious IOIs but she's playing game back at you, so you need to kick it up a notch with negs and being cocky/alpha. don't be all excited about it, this can screw you over. just act like you're in control, they'll love it. tell her how it is, how she's going to be your slave or something, etc... hopefully you can take it from there if it goes this path.
when girls play game back at you, i get shocked sometimes, and i turn afc for a quick moment... then i'm back to square one and i have to redeem myself. so you need to learn from experience.
anyway, good luck.