Human-centric processes are part of most organizations and their execution steps are typically not known initially. Consequently, standard business process modeling approaches are not suitable for modeling informal processes because they typically concentrate on the explicit modeling of the execution steps. In this work, we analyze properties of informal processes and requirements for supporting their correct enactment. We review existing approaches and evaluate their suitability in terms of modeling informal processes. Based on these results, we present a resource-centric approach by employing the concept of Informal Process Essentials which is used to create executable informal process models with dynamically changing interrelated resources.