Jakob Nielson, the guru of web design and usability (literally, the guy practically invented the field), has five design principles that should form the core of any proposed website. He wrote these over a decade ago. However, ask yourself how many websites you know that follow these?
I am guilty myself of avoiding some of these.

-Learnability: How easy is it for users to accomplish basic tasks the first time they encounter the design?

-Efficiency: Once users have learned the design, how quickly can they perform tasks?

-Memorability: When users return to the design after a period of not using it, how easily can they reestablish proficiency?

-Errors: How many errors do users make, how severe are these errors, and how easily can they recover from the errors?

-Satisfaction: How pleasant is it to use the design?

Can you think of five websites off the top of your head that follow more than three of these at any given time?