Things to look for when buying spectacles

Being a spectacle wearer for a significant portion of my life now here are the things about various glasses that I bough that annoyed me in the past: 

• Glass should NOT curve with the face : otherwise everything looks weird ... sort of like tunnel vision. 
• A nice vertical view angle is just as necessary as a nice horizontal view angle. I came to notice this when I played snooker. Also it helps to have the eye + eye bags inside the rim. 
• Size : some glasses are too wide for my face. 135 suits my face fine. 
• Balance : It is nice to have glasses that sit comfortably level to the ground on your face. This can be adjusted with nose-pads preferrably. 
• Center : Both your eyes should be at the center of the glasses if possible :) 

Enjoy!