Leslie Vail now has a handy Quick and Dirty Checklist for Modifying Word Templates
Dynamics Confessions Blogspot: Quick and Dirty Checklist for Modifying Word Templates
Payables & ReceivablesExcel & OfficeTips & Hidden Features
Archived post from 2016. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.