Check out this article on Estate planning from Forbes:
“Your will is your single most important estate planning document for many reasons. Generally, the attorney drafting your will also prepares ancillary documents such as power of attorney, living will, and health care proxy – all quite important. But there is also a very meaningful (and extremely considerate) part of your estate planning that doesn’t come from your attorney, and in fact, has absolutely no legal standing whatsoever. Your Letter of Final Wishes (LFW) is a direct communication between you and your family that provides them with a great deal of useful information that doesn’t belong in your will.
Your LFW addresses what arrangement you want made for your funeral and burial, those you wish to have notified of your passing, desire for a military service, perhaps a draft or outline of your obituary, and maybe even the program for your memorial service. Taken to the extreme, one person I know quite well (me) even included the playlist for the memorial service (“Tears in Heaven” brings out the tissues; “Stairway to Heaven”/”Highway to Hell” keeps them in suspense; “Every Breath You Take” puts everyone on notice).
Your LFW also can contain the myriad of personal details pertaining to your life and household—from the important to the mundane, perhaps including electronic information such as online accounts, IDs and passwords.
We recommend that you logically structure your LFW into sections. For example, you may want to start with details for your final arrangements, and perhaps discuss your thinking behind some of the more unique provisions of your will (“…as my son Jim is a neurosurgeon, and Little Billy is an intern at Goldman Sachs, I’m bequeathing 90% of my estate to Jim as obviously he has far less earning potential…”)
Next a section on important, but non-legal, issues such as the new home for your pets, notification to fraternal organizations and societies, suggestions on the use of collective gifts such as a boat or vacation home. Of course you should include a section that pertains to your financial life including the location of documents such as tax returns, pension and investment statements, and important contacts (attorney, accountant, banker, insurance agent). For further suggestions, there are many online guides that can be very helpful.
From personal experience I can advise you that including more rather than less detail will be greatly appreciated. Many of us have gone through the ordeal of winding down the affairs of a friend or family member. As a guide when preparing your LFW, reflect on the information you wish was easily accessible, answers you wish you had at the time, and expansively include your personal knowledge that may be helpful. As a final note, unlike your will which may not be readily accessible, your family should know how to access your LFW, whether a physical document or online.”