This paper presents experiences obtained from our involvement in the development of industrial simulation projects. Some important, common questions are covered, such as the need to define model behavior using a conceptual model, the problem of choosing the appropriate tool to code the model, and the validation and verification process required. As we will see, the scope of applicability of simulation is broad and the tools are therefore diverse. A clear understanding of the objectives of the simulation, the client’s aims and the resources at our disposal are key issues that often determine the success of a simulation project.