In the paper, we investigate principles for modeling flexible business processes enhanced by business rules. In our work, we start from a set of rule patterns, which are identified in the literature as a mean for increasing flexibility of business processes. The previous work on these patterns only considered the implementation level, but not the implications on the modeling level. Moreover, the potential for business process flexibility have not been fully leveraged due to some limitations in externalization of business logic into business rules. In this work, we report on the experience in modeling the set of rule patterns by using a rule-enhanced business process modeling language (rBPMN), and demonstrate the applicability of our findings on a business process case study.