What are the best thumb rules for optimizing website via CSS?

The best thumb rules for optimizing the website via CSS are:

• Fewer Images
  
  Use sprite image
  Use font base CSS Icons
  Use CSS styling text instead of graphic text image
  
  
• Organize CSS Code
  
  Reduce unnecessary code
  Shorter Class and ID Names
  Document your code
  
  
• Less Usage CSS Hacks
• Put the CSS file on top
• Minimize CSS Code