Here are 5 important elements to keep in mind for improving the ease-of-use during the design process.
Is It Learnable: How easy is it for users to accomplish basic tasks the first time they encounter the design?
Is It Efficient: Once users have learned the design, how quickly can they perform tasks?
Is It Memorable: When users return to the design after a period of not using it, how easily can they reestablish proficiency?
Is It Error Free: How many errors do users make, how severe are these errors, and how easily can they recover from the errors?
Customer Satisfaction: How pleasant is it to use the design?