According to the preface, what is considered the most effective form of service through writing for achieving salvation?

The preface asserts that the best and most certain service in writing that grants the fruit of salvation is to write the biography of one's Sadguru. As detailed in Chapter 0, this act should be undertaken either by the Guru's command or by inner inspiration. Furthermore, the service is completed by personally studying it regularly, performing hundreds of readings (Parayans) and weekly recitations (Saptahs) with a pure heart, excellent faith, and unwavering devotion. This type of service, which engages the body and speech, is considered the highest form and does not interfere with maintaining one's family life.