Jenn Fortner (Assembiles of God coach) has written a very helpful downloadable e-book on taking a relational approach to MPD.
Financial Partnership Development : Fundraising Made Relational is a 150 page manual with everything you need to develop your financial support.
Financial Partnership Development is an interactive and comprehensive workbook on fund-raising. Originally written for Assemblies of God World Missionaries, the workbook trains readers step-by-step in biblically and practically raising financial support. Combining teaching and 7 guided assignments, it is designed for both small groups and individuals. Readers will grasp ways to raise finances with individuals and churches. More importantly, they will learn how to minister to their financial partners along the way.
It is available from various sources as a Kindle or Kobo e-book or a pdf.