I agree that the "tech" side of things is also important, and something that people often don't think about. I went through this last year with my father and stepmother after my Dad was diagnosed with advanced lung cancer. Here are my suggestions:
Email account(s) - my Dad and stepmother were logged in to his email account on his laptop and both their phones. As a result, neither could remember the password as they were always logged in. But that account was their joint email address, in effect, so it was vital not to lose access to it, which might happen if someone tried to log in from a new device (like a new phone). We agreed a new password, changed it and then wrote it down. Also consider the backup access for the account if the password is forgotten - his sent a message to his phone, so we changed that to my stepmother's phone number.
Other important log-ins that family will need - write them down. I know it's not best practice, but needs must. Get an indexed notebook and write down usernames/passwords to key sites in it, so that they are all together.
Security - turn off retina scans/fingerprints etc on gadgets and go back to passwords. I work with someone whose husband did all the tech and finances in their household and he died suddenly. His laptop, containing all of that information, could only be unlocked with a retina scan so she couldn't access it. No doubt there's a way if you're a super-techie, but that's not what the family needs after a bereavement.
Paperless accounts - go back to paper for utility accounts to be on the safe side, particularly if the account is linked to the email address. (This is also important if you live alone, because if you die suddenly and relatives cannot access your email or computer, they will have no idea who your phone company/electricity provider/broadband etc is and won't be able to notify them/cancel the services when necessary. Some utility companies offer savings if you go paperless, and some just change you over regardless (thanks EDF) but it's worth changing back for peace of mind).
Subscriptions - cancel anything that's going to automatically renew. The renewal will fail if the bank account has been closed and then there will be hassle.
My main tip is not to wait. "Months" are not necessarily months. My Dad died five weeks after he was diagnosed. However, he knew by that time that everything was in good order (we also had meetings with his lawyer and financial adviser to double-check that his will was OK and that he had signed any financial paperwork necessary) and my stepmother would not have to worry about any of this stuff.