How do I know if she's interested?

[Matt]

I really like this girl but I can't tell if she is into me or not. We were at this party together and to start the night off she came up and gave me this huge, lingering hug. I would say it lasted at least 30 seconds. Later in the evening we were in the basement together and a slower song came on (Angel by Shaggy), she embraced me, started swaying back and forth like she wanted to slow dance. This lasted about a minute until the DJ changed the song to Make it Nasty by Tyga and she walked away. About 20 minutes after this she found me again right when a faster paced song came on, she pushed me against the wall and started grinding on me. A few days after this I learned via Twitter that she loves when guys play hard to get. The times I text her and we talk for awhile she seems genuinely interested in the conversation but we have been to a few parties together since this night and she hasn't seemed as interested. Based upon that night at the party, do you think she may be interested in me? I don't want to overstep any boundaries. Also, how can I "play hard to get" just enough so she knows I'm interested but not too interested?

[jazmine]

Ask her out on a date

[Elisa]

OK, well obviously she was interested in you at first, but then you got too clingy, you said you'd been having conversations with her. If she seemed interested, then you were doing something right, but if she like guys to play hard to get, then do that.
How to play hard to get: don't message her unless you have something important to say, when she messages you, wait a bit, don't answer straight away. when you see her, don't go right up to her, just sort of nod in her direction and she'll get interested and probably come over to you later.
Next time you're at a party with her, if she comes up to you and does the same stuff like at the first one, don't just stand there and let her do everything- join in, maybe pull her into a corner and start talking to her.
Hope it works, good luck.