Well, it depends at the circumstances of your llife.
If you have a pet or more than a one, you must consider how they will care of them after you passed away.
If you have any minor child, what will be the next to take care of them?
Anyway, if serves as inspiration, here's my own to-do list:
- A suicide letter (This is a personal preference, since I don't want to put any responsibility of my decision to anyone, such as a partner, family member, workplace or transphobia / homophobia).
- Doing a delayed e-mail about my personal data, as I request to delete it from bank accounts or another accounts.
- Charging my phone to have enough battery to locate my position, as I'll be dead and I will not be seen at my work.
- A favorite liquor to enjoy my last moments of living.
- A "self mourning" period (it could be the same day of dying, or one day, or two days previously), to internalize the own process of dying.