Persistence works when you know when come on strong and when to lay back. There has to be an attitude about you:
There was this girl at my old job. I'd flirt with her, She'd flirt back. But I still couldn't get her to commit to a meetup outside the office. So sometimes I'd back off - turn off the attention faucet (attention is like currency to these girls). Then she'd come on stronger to get the attention back.
I'd say stuff like, "It's Friday. What are WE doing this weekend? Wine & massages?" Like I know her shy as* was gonna say no. But I wanted to get the idea across that I was trying to get with her. This wasn't some kind of friendship deal.
Or she'd say "My parents are away for the weekend..."
And before the sentence finished I'd say "So you're inviting me over?" Just playful funny stuff.
This works when the girl is shy or playing hard to get, but she's still INTO whatever game you're kicking. If a girl doesn't like you, this stuff won't work. It took like two months of toying around with her before I got her out of the office and in bed, but it taught me that "no" isn't always no. This was years ago...these days I feel like there are too many girls out there for me to sweet talk one for weeks at a time.
It's not that persistence is a bad thing, it's just that these days, I'd rather invest my time and energy in a girl who KNOWs what she wants instead of sitting around playing the "I like him/I don't know if I like him" game.