Modeling requires considerable knowledge of the various stages of the simulation process. The modeler needs to know a great deal of the system to be modeled (domain specific knowledge), the ins and outs of the modeling process itself (the degree of detail of the model) and how to implement the model in a simulation language. Each of these stages would benefit from some kind of knowledgeable support. In this article a decision-making process is described that supports the modeler to build a model step by step. As a vehicle the Arena simulation environment has been used. The support is based on information provided by the modeler and is essentially data-driven. It suggests which modules could be used best, which parameters need to be determined and helps to formulate route information. This research aims for an implementation of this support using a knowledge-based system.