Every method carries its own risk. I still consider SN somewhat scary, but if you're disciplined, then using it should be considerably peaceful. Slitting your wrists demands a lot from a person. Pulling the trigger isn't that ideal too, since the act itself represents that thin line of mortality a few can cross. Its one of the reasons why its "ideal" for impulsive and inebriated mindsets, yet of course those also come with the baggage of a possible fuck-up.
To each their own, though. Whether it'd be SN, N, exit bag, partial suspension (2nd fav option, personally), etc. If you do enough digging on this forum, then you can find some usable, valuable sources. You're already asking the right questions in this thread, but please consider each step thoroughly. There's a lot of good support in here for that.
'2m2b' is harnessing my attention as of now, but the shortage of sources and its unavailability in my hometown render it way too clandestine and dangerous to approach for now. Nothing will truly optimize you and your SI, so everybody has to make their own peace. Ctb is a tough business, even sailing away on N seems rather morbid, and it is...peace in passing sure does sound beautiful, but mainly to people here. That's why, most of the time, you can trust their sources. When researching methods, weigh the possible consequences and estimates of pain at your own merit.