Most of the Virtual Learning Environment (VLE) design methods focus on producing content for a VLE. However, usability of the VLE is also of great importance. Several potential usability problems have been reported in recent e-learning conferences. These problems could have been avoided by applying usability engineering methods before the VLE was taken into use. This paper describes usability engineering methods used to ensure the usability of Virtu, a virtual learning environment (VLE) concerning safety at work. The results of using each method are summarized and as a conclusion, some general VLE design guidelines are listed to help others in VLE design.