Software process improvement (SPI) is challenging, particularly for small and medium sized enterprises. Most existing SPI frameworks are either too expensive to deploy, or do not take an organizations' specific needs into consideration. There is a need for light weight SPI frameworks that enable practitioners to base improvement efforts on the issues that are the most critical for the specific organization. This paper presents a step-by-step guide to process assessment and improvement planning using improvement framework utilizing light weight assessment and improvement planning (iFLAP), aimed at practitioners undertaking SPI initiatives. In addition to the guide itself the industrial application of iFLAP is shown through two industrial cases. iFLAP is a packaged improvement framework, containing both assessment and improvement planning capabilities, explicitly developed to be light weight in nature. Assessment is performed by eliciting improvements issues based on the organization's experience and knowledge. The findings are validated through triangulation utilizing multiple data sources. iFLAP actively involves practitioners in prioritizing improvement issues and identifying dependencies between them in order to package improvements, and thus establish a, for the organization, realistic improvement plan. The two cases of iFLAP application in industry are presented together with lessons learned in order to exemplify actual use of the framework as well as challenges encountered.