I watched my father wage a losing battle against cancer. The only silver lining is that he had time to prepare for his demise. In doing so, he helped his grieving family deal with the transition without him.
This is the hardest of them all, but without accepting that the end is near on this earth, the rest is impossible. I will not simplify this step, as every person on the planet will have their own method, beliefs and fears to explore. Ask for guidance from your spiritual advisor, if need be.
PREPARE YOUR WILL
My father gave me many verbal edicts, all of which are moot in a court of law. If you really want your wishes upheld, prepare a proper will. If you can't afford an attorney, there are a few online law services that provide a template for the documents you may need. Don't leave your family in chaos; give them the directives they need to honor your wishes properly, including method of burial (if at all); location; service requested (private or public); division of property and assets; and naming power of attorney, among others.
ORGANIZE YOUR FINANCES & IMPORTANT PAPERS
The more organized you are, the easier it will be for your surviving spouse or family to sort through the many challenges they face, whether it involves real estate, taxes, car loans, etc. Keep it in a central place and make that location known.
SHARE YOUR PASSWORDS
If you have website subscriptions, now may be the time to "downsize." At least give your password(s) to your family so that they can deal with the internet sites later.
HAVE A LIST OF WHOM TO NOTIFY
Write a list of the family members, friends or organizations that you would like notified upon your death. Decide whether you want an obituary to run in any major newspapers and what information you would like to share.
TIE UP LOOSE ENDS
My father always wanted to visit his mother's grave one last time; not only to visit, but to replace the marker on her grave which was fading with time. He spoke of it many times, but he did not make the visit. Whatever the desire, the loose ends you want tied need to be tied by you.
Many families are fractured; not everyone gets along. History may have long-standing feuds. Do your best to put these to rest so that you can provide that elusive "closure."