So, there's this girl I met on tinder. Exchanged numbers and after that she used to call me. I was playing hard to get with her but I Took her out twice and she seemed pretty interested. Now when I call her, she's either busy or she's doesn't pick up. How to proceed now?

P.S.- I don't text her much but she knows I hang out with a lot of girls and we talk very less. How often should I call her?