Some situations are simply no win, but ethics demand you do your best. I've wandered through this particular adventure once, and observed others about the project.
Someone passes, and you're the one tasked with staying sane/responsible...or worse yet, you're the executor in a morbid bonus round.
First, somebody is going to be pissed at you no matter what you do. Accept that, and reduce your stress level by half. There will be no pleasing everyone, and that's just too bad. Move on, suck it up, you have work to do.
From the moment the decedent passes and you find yourself in charge, there are duties that need attention. Most hospitals will not release the body until a family member or next of kin has taken possession of any immediate belongings, particularly and especially jewelry and such.
My experience was that a nurse helped me, and we inventoried as we went, and cross-signed verifications in an attempt to head off any ugly little questions. There is no need to rush right up to the grieving widow or family, but conveying said personals along with a *copy* of the inventory within 24 hours is a *really* good idea.
Again, the best way to avoid drama is to ensure that the preconditions simply don't exist.
Once the body is released to the funeral home du jour (this assumes one has been selected in advance - you've selected yours and made sure the proper folks know, right?) see about a will (if any). Then talk to the family...my formula was "Decedents wishes first, spouse/partner 2nd, all others rate 3rd tier or below...and it seemed to work for most decisions.
Odds are good you'll be *making* a lot of the funereal decisions, but to the extent practical, do so in deference to the formula above. Then, to the extent practical, go class every step of the way.
A service should comfort the family, not traumatize. You'll be faced, more than likely, with a conflict between the kumbayah crowd and the formalists - each want to take comfort and reassurance in rituals that fit their image of the "one right way".
Compromise, default to tradition where you can, and if you must, arrange separate services. One compromise can be found in the formal service, followed by a casual reception with the best food you can afford (cater if you can...this is NOT the time to burden yourself or the family with a big cooking frenzy)....and in many cases, a full bore wake later in the evening for those that believe in *celebrating* the passage of family or a dear friend to a better place, and the joy and love they brought to the lives of those around them.
Then comes the "disposal of the crud". I suspect that between 75% and 90% of what we surround ourselves with, while really neato to us, to most of the rest of the species is just detritus and crap. And that's just fine. While we are still kicking we enjoy it, and once we're gone it's not our worry.
But when we pass, particularly if we haven't made our wishes clear (and legally binding), sorting out what has sentimental value to who and what is just crap...gets REALLY challenging. And then there's whats offensive or heartbreaking. Uncle Bob may not want his last memento of Cousin Willie to be Willie's Earwax and Toe Cheese Sculpture collection...but he might want that beat up old work shirt of Willie's that Willie wore just before he saved Bob's life in the big crotch alligator incident. And that's before we consider Aunt Sassy and the spoiled grand-daughter Melchior.
Assumptions are bad. If anything is left after the instructions in the Will (if there is one, otherwise just skip ahead here), start asking privately and doing the negotiation dance. Kindness and consideration for the win - you've just been nominated to get only what nobody else wants, unless everyone explicitly consents. There may be keepsakes you miss out on, but the drama you avoid is worth every moment of regret.
Do your best. Be honorable as you understand the notion. Set aside your personal interests in the interest of fairness.
You'll piss SOMEONE off, almost certainly. But you'll sleep well at night.
YMMV. IANAL. Seek professional advice as needed. And if you're on the other side and someone else is in charge? Don't be a jerk. Be helpful, don't sweat the small stuff, and don't start multi-generational pissing matches.
Besides...the high road is better ground from which to hurl offal upon those who annoy you, later.