Internet has brought to cultural institutions the chance to use new communication paradigms. In particular the introduction of 3d technology for the network promises to be a powerful means for the diffusion of scientific and humanistic culture, especially for novices that could find a more intuitive paradigm to access cultural information in the 3D metaphor. This work analyzes the current points of weakness of navigation in 3D worlds and proposes new guidelines to improve the quality of interaction for cultural heritage applications. A particular reference is made to naïf end users which may be experts in their special application domain but are generally not capable of orientating, navigating and exploring within virtual information and knowledge environments, due to the lack of support provided for these activities by nowadays information systems and their 3D-visual front end architectures and tools. The paper proposes a number of guidelines to overcome the current limits in 3D interaction and to help authors to build more effective 3D simulations. These guidelines have been applied in a number of implementations made for the Palazzo Grassi web site (Palazzo Grassi is the world wide known institution that promotes cultural exhibitions and events in Venice); these realizations have been precious for receiving feedback from users and for refining the proposals, according to the principle of interactive design.