According to the preface, what is the most effective way for devotees to serve Sai Baba and build a community around his teachings?

The most effective way for devotees to serve Sai Baba, as outlined in Chapter 0, is through the creation and study of his detailed biography. The Sadguru is said to take service from devotees by having his biographies written and then accepting service in the form of study and Parayans from the writer and the congregation. This act is not just a personal service to the Guru; it is also a public service. When other devotees study and perform Parayans of the work, the writer gains the merit of serving God in humanity, and the participating devotees are helped to achieve the purpose of their lives. This shared practice, centered on a work like the Shri Sai Satcharita, is foundational to building a community.