Gerald F. Hess (Gonzaga) & Sophie M. Sparrow (Franklin Pierce) have published What Helps Law Prpfessors Develop as Teachers?— An Empirical Study, 14 Widener L. Rev. 149 (2008).  Here is the Conclusion:

What are the most effective faculty development activities? It depends. Teaching is complex, and there is no one right way to develop as a teacher. Survey data suggests that faculty benefit from engaging in a range of different kinds of activities, three of which are reported to be the most effective. Reflection by individual faculty members—thinking about their teaching before and after class, writing about their experiences in a journal, and gathering feedback from students during the course—has enormous benefits. Similarly, discussing teaching and learning topics with colleagues in formal colloquia or casual conversations increases teachers’ awareness and knowledge of teaching principles and also boosts their confidence and passion about teaching. Finally, the overall most effective faculty development activity is having law faculty attend national or regional teaching and learning conferences. These different kinds of activities likely combine synergistically to more fully inform, challenge, inspire, and engage law professors than any one activity would alone. Law schools that are serious about improving teaching and learning should offer, support, publicize, and promote a wide range of faculty development activities, with the understanding that the needs of the faculty will evolve over time.