Most guys who get every woman they want to have "developed" their own stance. Like in sports, you've to learn a specific stance! Never show your stomach, hold your head up and back, pull your shoulders back and arch your back. This may sound ridiculous, but this self-confident postion allows you to act like the owner of this hunting-ground. It will feel strange for the first times, but you need the practice! Always remember, that women don't look out for softies or loooosers. They look for self-confident men.

Walking around like Montgomery Burns will attract nobody, I swear. Women always want muscles and a nice body. If you don't have a model body - doesn't matter. But try to make the best out of it.