Cloud computing has recently emerged as a convergence of concepts such as cluster computing, grid computing, utility computing, and virtualization. In hybrid clouds, the user has its private cloud available for use, but she can also request new resources to public clouds in a pay-per-use basis when there is an increase in demand. In this scenario it is important to decide when and how to request these new resources to satisfy deadlines and/or to get a reasonable execution time, while minimizing the monetary costs involved. In this paper we propose a strategy to schedule service workflows in a hybrid cloud. The strategy aims at determining which services should use paid resources and what kind of resource should be requested to the cloud in order to minimize costs and meet deadlines. Experiments suggest that the strategy can decrease the execution costs while maintaining reasonable execution times.