When a girl is flirting she will fidget with her hair or if a necklace if she has one on. When a girl is fidgeting with something it means she's feeling girly and wants you to think of her in that way.
When a girl wants to hook up with you she will try to get really close to you. And if you move back you'll notice she will move towards you again. Women don't get close to people that they are attracted too.
When a girl is touching you it means she wants you. She's hoping that by touching you that you'll touch her. Especially if she's touching your arm and chest, that means she really wants to fuck you and you can definitely make your move.
Sometimes girls don't want to be to forward with touching or sitting too close. But if she is giving you an unusual amount of compliments is can mean she wants to get in your pants. Girls love words of affirmation, so when she starts giving them to you, you can be sure she wants to fuck. Also if she laughs at all your jokes she's probably really into you.
Sometimes girls like making sexual innuendos just for fun. But if she's making sexual innuendos and doing any of the other signs above, it means she wants to fuck you. Bad.
If you've made plans to hang out with a friend whos a girl alone and she shows up is a sexy revealing outfit. You can assume she wants you to make a move because she probably wants to fuck you.
Unless this is a habit of hers, which is difficult to fake, if she's licking her lips, or biteing them, it means she's thinking about yours and wants to kiss... and probably fuck you.
This is really difficult to fake. If a girl is breathing heavily and you're both just talking it means she is really turned on by you. The more interest she shows in you the faster her heart rate increases which will make her breathe heavier, which means she wants to have sex with you.
If you're texting a girl and she starts to make things sexual, it's pretty clear she's thinking about fucking you and wants you to make a move.
Similarly to sexting, if you're texting a girl and she says something like I'm bored or that her plans got canceled it means she wants you to know she's free. She probably wants you to come over a hookup but doesn't want to directly ask you.
If a girl is interested in your sexual history it means she's thinking about wanting to fuck you. Girls like to know where a guy has been sometimes before hooking up, so if she asks you either directly or indirectly about past hookups it probably means she wants to fuck you.