There has been a recent push to increase the practical relevance and impact of software engineering (SE) research. Even though many practitioners and researchers agree that this change is desirable, only some concrete actions have been taken in the community so far. In this paper, we present our experience in a large number of collaborative research projects (26 projects) which have had practical (industrial) impact. These projects have been conducted in several different countries, have focused on different SE topics (e.g., testing, software maintenance, and documentation), and have spanned over different domains (e.g., embedded software, defense and telecom, robotics). We characterize the industrial needs, contributions, and impacts of the projects. Furthermore, via a participant-observation research approach, the authors analyze their diary reflections recorded during the projects and synthesize their experience into a set of seven lessons learned on how to conduct successful industry-academia collaborations. Our hope is that the evidence and experience provided by our example projects would motivate SE practitioners and researchers to engage more on collaborative projects.