To get exactly what you want.
I am being ironic, a little. But I find this to be so close to the truth I had to write the title. This is how you go about it. Take it with a pinch of salt but the essence is here.
Look directly into their soul.
I bet you were not expecting me to say that. But you do. With your gaze completely unwavering and with no guile or malice or alternate agenda greet them with the full you. You project your complete honesty as a person to the other in this moment. It's almost a way of entering their psyche. For that moment you become completely a friend and an equal with them.
Your speech has a balanced timbre that resonates with them. It is stressless and talks to them as if you have known them forever. It's a sound that for them comes from within them. They feel your purity and your honesty of intention.
Then you ask for what your want. The same voice the same tenor. It just comes from the middle of you. There is no expectation in your tone, no push no doubt. You are talking to them from within them, partnering and being part of them.
Then you get what you want, and if it doesn't look like what you wanted. Try again. Life works better when we partner with another and they choose to be with us. Choice sets us free.