Ya, the "how can I guarantee she will come to me and not other customers", the answer might very well be JS69's technique of flashing hundreds of dollars and basically implying that he's going to spend more money than anyone else there. It's so not my style that it's not something I'd personally do, but if it IS your style, I think JS69's way is probably as foolproof as it gets.
For me, I will tip her, and just say "if you're not with any customers right now, I'd love to buy you a drink and get some dances, I'm sitting over there." In the very slow shifts I go to, this tends to be enough. During busy shifts, there's definitely no guarantee.
galiziabob's approach is kind of cutesy and fun, if it's your style, gets your point across about doing a VIP without coming across so intense