I have been severely depressed for about 30 years, so I've done a lot of thinking about it, generally, for a long time. Did a lot of reading on suicide, both academic and news reports and the like from "suicide survivors" (people who have loved ones who've committed suicide) to get an idea of what people say makes having a loved one die or commit suicide worse and what they say makes it a little easier. Also have a lot of second hand experience with suicide and death in general from friends and family in fire service and medical fields, as well as some first hand experience from a failed attempt of my own that was detected and got me committed more than a decade ago. (Gave me some insight regarding my loved ones' individual reactions and preferences, specifically.) I also have a career that requires a lot of planning and creating resilience/redundancy, so that undoubtedly helps, too.
As best I can figure out, the important things as far as surviving loved ones are concerned are to provide for them materially (money, things, save them effort after the fact) and provide for them emotionally (absolve them of blame, provide answers, express you love them in a note, give them good memories to look back on, and mementos/souvenirs if possible). I did a lot of research and have more experience than most regarding death and suicide, so that helps, but I think that just putting yourself in others' shoes will give you a good idea about what to do and what not to do. ("If my friend/relative killed him/herself, what would help me deal with it and what would hurt?")
A good plan and the time to put it in place are worth a lot. Several months ago I decided there was a good chance I'd be CtBing soon (and a few months ago I made the decision for certain), so I started doing specific research on methods, mapping out good times to go (avoid birthdays, holidays my survivors care about, etc.) and writing up lists of things to get sorted out before I go, things that otherwise couldn't get done, or things one of my loved ones would be stuck doing. A lot of it was minor stuff (send those pictures to that friend, clean up/throw out that junk in the spare room), but some of it was major stuff (get that will made, make sure the beneficiary on that account is updated). Going through day to day life provided me some reminders of things that hadn't come to mind, so having time helped in that regard, too. Crossing things off the list led to other things (like, this would be easier for everyone if I put this stuff in storage, so I'll go rent a storage unit, oh and that friend's TV sucks, I'll give her my spare big screen instead of boxing it up, etc.), so a lot of it flows organically from just having a goal and a list of things to do to achieve it.
Mostly the same deal for the emotional side of things, too, but that just seemed to come together from thinking it through, knowing a bit about the grieving process after the death of a loved one and knowing what my lived ones like and don't like. Being "missing" prevents closure and drags out processing an estate, so I need my body found. Having a loved one find the body or leaving a gory corpse are traumatic, so I need the cops to find it first, so I'll go out in a hotel room or accessible nature location, using a peaceful method. I'm having trouble compressing my carotids, so I'll use the exit bag. Want the cops there before some random person stumbles across a body, so I'll send out scheduled texts to 911. My next of kin hates packing and moving stuff, so I'll get my stuff packed up and moved. Funerals and the disposition of the body are for the benefit of the living, not the dead, so make sure to say it doesn't matter to me and I'll be OK with whatever they want. Suicide notes are for the living, not the dead, so eff making a statement or a expressing myself, focus on answering their questions and dealing with their emotions. They all want to spend time with me, and I want to leave them with good memories, so take leave from work (or quit) and spend time with them and doing things for them. Dad hates mowing his lawn, so I'll drop by on the weekend, mow it for him and then we can have some beers, grill up some burgers and laugh about Trump wanting to buy Greenland. This friend likes fishing, so I'll go out on the lake with him for that (ugh), and that friend wants to see some terrible movie, so I'll buy some tickets and watch it with her (at a theater that serves alcohol, because being a bit buzzed will help me get through it). And so on.
At least for me, like most things in life, it's about figuring out what you want to accomplish, thinking through how to do it, turning that into a list of things to do or a pseudo plan, and following through. It's also my top priority (relatively speaking, nothing else matters to me), and that's very motivating. I've found the process of planning and looking after my loved ones helpful for me personally, as well - laying out my reasoning and analyzing my situation helps dispell any of that false hope that's made me hesitate in the past, no more "I need to get [blank] done before I die", and I'm less concerned about my loved ones, since I've looked out for them. Helped my mood, too... less anxious and worried and so on, more confident and stoic about things now.
That's my basic thought process, hopefully it helps. If you don't have the time to do everything you want to do, prioritizing helps. Figure out what things you want to do, rank them in importance and get through as many as you can before you go.
