It normally happens naturally, like with gay guys. I always find it hilarious watching them strut their stuff. But, I guess if you really wanted to, you could practice it in front of a mirror.
You have to pick either the x's or y's and make them equal to eachother. It's kinda like trying to add and subtract fractions. You need to multiply the whole equation by a number on both sides and then multiply the second by the other number that makes either the x's or y's equal in both...