Graphs provide good representations for many domains. Interactive graph-based interfaces are desireable to browse and edit data for these domains. However, as graphs increase in size, interactive interfaces risk information overload and low responsiveness. Focus+context approaches overcome these problems by presenting abridged views of the graph. Users can then navigate among views with a level-of-detail mechanism. If jumps from each view to the next are easy to follow, users will gain a good mental map of the whole graph; otherwise, they may become disoriented. In this work, we identify three factors that affect mental map preservation during navigation of interactive focus+context graphs: the predictability of navigational actions, the degree of change from one view to the next, and the traceability of changes once they occur. Strategies for preserving user orientation are classified according to these factors, and new strategies developed for the CLOVER visualization environment ar...