Not to sound repetitious, but attraction or "chemistry" is a personal preference. Everyone is different. What may be attractive and totally chemical to one, may be a complete turn off to someone else.
I look at the person as a whole. I get to know them. I am more interested in their personality,intellect,humor and sensuality than just physical appearance. What is right for me may not be for you or anyone else.
You need to decide what you find attractive and sexually stimulating. When you meet someone who has these traits, you will know if there is any chemistry or not.
mrs. hmr