Agent-based modeling (ABM) is quickly becoming a choice tool for researchers, as it is very adept at modeling natural phenomena. Spatial data has the ability to further increase the usefulness of an ABM. One way that this can be achieved is through the inclusion of geographical information system (GIS) data. Such integration between ABM and GIS may sound trivial, but it is difficult to do effectively, particularly as the complexity of GIS data and the amount of agents increase. Here, we present methods and recommendations on including GIS data in a complex simulation model. We demonstrate our techniques on an advanced epidemiological model.