There is a game. You ask for or state or express what you want, and then you either get it or you don't. Whether you get it or not doesn't really matter, what matters is that you don't flinch.
If you flinch you're almost certainly not going to get what you want. If you flinch you interrupt a beautiful pattern of shared context with a sudden injection of fear or doubt or neediness. If you flinch you express a hidden conviction that you don't deserve what you claim to want, and so your outer expression doesn't match your inner state, and isn't that a little suspect?
I love the flinching game whenever I don't flinch. I can't stand the flinching game whenever I flinch. So the game beyond the flinching game is learning how to not flinch, how to stand firm.
As with many things I think experience is the best teacher. Play the flinching game a lot. When you flinch, sit with the feelings that surface and observe how it's not that big of a deal, it's just a game, you're okay.
Other people are good teachers too. You can probably think of a famous person who rarely loses the flinching game. Watch interviews with them and notice qualities that serve the conversation such as their body language and their attunement to their conversational partners.
You can also teach yourself by recognizing that much of life is a sort of flinching game you play with yourself. Did you do what you said you were going to do today or did you flinch? Did you treat your body well today or did you flinch? Did you choose kindness over cruelty today or did you flinch?
When you know what you want and you express what you want in ways that are authentic to who you are, you make the world around you a better place.