Smaller software companies, such as start-ups do not often follow an explicit process, but rather develop in a more or less unstructured way. Especially when they grow or customer involvement increases. This development without any structured process results in problems. Thus, our objective was the improvement of the current development process of one software start-up by introducing appropriate agile practices and eliciting their effects. For this reason, we per-formed a pre and post process assessment using interviews. Based on the initial assessment, agile practices were selected and implemented. Finally, the post assessment and additional code metrics served as controlling mechanism to check whether weak points are addressed. The comparison of the two assessments showed that 13 ISO29110 base practices have been improved by the introduced eight agile practices. Thus, even more aspects have casually been improved than initially planned. Finally, the additional retrospective with company employees showed how the introduced agile practices positively influenced their work.