This is basically just a physical thing, but I've found it's got merit:

http://www.businessinsider.com/tips-attractive-guy-2014-4

  1. Wear Red
  2. Heavy Stubble
  3. Good Posture/Sit Up Straight
  4. Smile Less
  5. Be Muscular
  6. Sweat More

Regarding #6, this is important for screening for women who are naturally into you rather than having to win them over a la PUA. If puts her face into you and says she loves how you smell, you're golden. And we're not talking about going to the club staight after a hard workout, so use your brain here.

This video has some more points, but there's not really anything you can do to improve them. I'm just including them as background info. The only exception is height, which can be modified by wearing boots and/or lifts in your shoes.

http://www.businessinsider.com/physical-attractiveness-2014-3