The diversity of Virtual Environments (VE) applications makes it necessary to design VE interfaces that support domain-dependent needs. However, some tasks such as navigation and manipulation are common to all VE applications and are essential even when they are not the main objective of a user in a VE. Inadequate support to user navigation is likely to result in users getting disoriented, leaving the VE before reaching their targets of interest, or leaving users with the feeling of not having adequately explored the visited VE. This project has two main goals: (i) investigate user behavior in VEs and (ii) propose possible solutions to the navigation and manipulation problems. With respect to the first goal, we are designing tools that are able to record and provide abstract representations of user interactions in a VE, helping designers to evaluate VEs by visually analyzing how users really navigate them. With respect to the second goal, we are designing and studying the effectiveness of different aids for navigation and object arrangement.