Much of the content of this book comes from survey done among a small group of returned missionaries who had been home at least three months. Some had been home for over three years. The survey simply asked respondents to rank order a list of ten habits that had been helpful to them in their transition home from full-time missionary service.
You can access a copy of the survey at The Best is Yet to Come - SURVEY.
Elder L. Tom Perry's General Conference address in October 2001 lists three important fundamentals for returned missionaries:
2. Personal and "companion" scripture study; and
3. Continuous engagement in missionary work.