Usability is linked to the 10 Usability Heuristics and User Experience design.

The key thing to remember here is to make the system as easy to use as possible for the largest number of users.

Questions that you should consider are:

  • Is it easy to use?
  • Does it follow the usability heuristics?
  • Can the user avoid and correct errors?
  • Does it use standard conventions?
  • Does it match the real world?
  • Does the system let you know what is currently happening?
  • Does the system provide appropriate feedback?

See the Nielsen Group for more information.