All the advice for these kinds of situations usually falls somewhere on the line between:
A: "It's not your fault - there is nothing you can do about it" and
B: "You messed it up"
There is truth to "A" and it helps guys who are overly hard on themselves for things that are outside of their control.
There is truth to "B" when a guy is turning a girl off.
My experience has taught me that 60% of it has nothing to do with you. You just aren't her type, she's not in the right head-space, she's talking to another guy, the timing is bad, whatever. "Nothing to do with you" is a bad way to put it because it might have everything to do with you but what I really mean here is that it has nothing to do with anything you've done WRONG or anything you can CHANGE and do differently. She might be into fat guys, or guys with crooked noses, or guys with a high voice or guys with bad beards. So since it is outside of your control, there is ZERO point in concerning yourself over it or feeling rejected. It's a square peg in a round hole.
So that covers "A".
"B" is "game". One could spend a lifetime mastering all the nuances of it, and you will always get better over time, slowly, with lots of practice. But from my experience, so long as you are doing the following things, you can chalk up any losses to "A" instead of "B":
1. You are being a challenge. This means you coming from the mindset that you are out to evaluate her and she has to prove herself to you instead of you hoping to god she chooses you. Once you get into this mindset, it will manifest itself in all actions you take with her. A recent example is a girl I'm dating who is 20 years younger than me. She lives in another country and is coming to stay with me for a month over the holidays. She told me she was worried I'd get bored with her being around for a whole month. I could have said, "I wouldn't get bored with you! I can't wait to spend a bunch of time with you!" Instead I said, "The only way to find out is for you to spend a month with me." Do you see the difference?
Nearly everything else about game is linked to the above. If you carry that mindset, all the other things fall into place. But to explode them out a little:
2. You are not acting needy
3. You are very careful how much you validate her, and in what ways (most blue-pill guys over-validate, and focus on the physical). Validation should be used as a reward, and it should not be out of balance with how she validates you
4. You understand push-pull and when to withdraw your attention and how not to be over available - and you match your investment level with hers. IE if she is not investing much in you, you don't invest much in her
5. You are assertive and dominant and lead the interaction
Honestly, if you get into the mindset of #1, you can pretty much attribute all your losses to "A" - not your fault, even if you don't do everything else perfectly.