What a wonderfully general question! You want me to give you an effective answer no matter who you are, who the other people are, what the relationship is like! Challenge accepted!
So, let’s break it down, what does it mean to win someone’s heart? Thinking about it, this boils down to two decisions you want the person in question to make. First, you want the other person to think of you above all the others. Second, you want them to sacrifice themselves to their relationship with you.
With my current girlfriend, I have accomplished the first but not the second. I can tell you how to beat everyone else, and the answer is simple but nowhere near easy. Took me a few years myself to get there. You have to meet her needs better than all the others.
Ever hear this old joke?
A bear jumps out of a bush and starts chasing two hikers. They both start running for their lives, but then one of them stops to put on his running shoes.
His friends says, "What are you doing? You can't outrun a bear!"
His friend replies, "I don't have to outrun the bear; I only have to outrun you!"
Achieving primacy over her other guy friends is a ‘simple’ matter of outrunning the bear. If you’re motivated and careful it’s not hard at all, even over extremely attractive women.
With the other goal, getting them to prioritize their relationship with you over themselves, that’s a way, way more difficult goal, made exponentially harder by their inherent resistance and un-readiness for relationships in general. The girl whose guy friends I’ve beaten out, grew up outside of the US and simply doesn’t understand what US relationships are like. This makes my task ten times harder than I thought it would be.
Really challenging, but until I find someone I like better, I have to take my best shot at it.
My guess is that in order to make this happen, you have to, not just meet her needs better than the others, but you have to actually meet her needs. You’re not just dealing with others anymore, you have to actually understand her. So, so difficult. Not being able to read her mind is no longer an excuse.
Best of luck to you in your endeavor.