I'm passionate about this one.
Initially I was all about the charcoal method (prior to joining this site and when I initially joined it). Around 2 years ago I learned about it and just figured when the time came that this was the no brainer suicide method. I was wrong. It's definitely not as easy at it initially seems. So many people attempt it and so few succeed (at least in the US that is, apparently in Asian countries they have a higher grade of charcoal that does the job). You need a copious amount of charcoal (2 goddamn bags), 2 medium sized charcoal grills or chimney starters, which requires a bunch of shit (water, bricks, metal buckets, etc, if you're in a car good luck). There's no general census as to how long you're supposed to let the charcoal burn vs when you move yourself in, but you just play around with it and feel it out I guess. Many people who attempt the charcoal route, start to feel ill and uncomfortable before they pass out, so they pull the plug on it. If you do this method, the best and easiest option by far is if you have a house. An apartment is a no go. The second best option is a vehicle as long as you know a remote location where you are guaranteed not to be interrupted. If you use a car I recommend going the 2 medium charcoal grill route. Lastly the tent method, which is not as easy it would seem. You need an exceptionally good/expensive ultra waterproof tent or else it will not work. Since you're likely going to need to use a car to carry all of the shit you need, you may as well just use the car. And lastly if this method doesn't finish you off you could end up as a vegetable.
After I realized that the charcoal method was no longer a possible/realistic option I researched further and came across the exit bag method and SN. I won't break down the exit bag method, but it seems like the second best option besides SN.
SN is by far the most ideal method to use. It's easy to get, it's relatively peaceful (it's as peaceful as Carbon Monoxide according to the PPH, but way less technical and more effective) and there is no chance of ending up like a vegetable if it fails.
Don't led the antiemetic protocol dissuade you because it's not essential to the process... you could use ginger as an antiemetic and it's just as effective and an antacid and you're good to go. This method initially seemed a little scary since most people who use this method will hurl (whether they use an antiemetic or not), but you keep a second glass ready in case this happens, which will seal it (even if you throw up your body will absorb enough). Even if you do throw up from it, it doesn't last long, most people loss consciousness in less than 1 minute from that time. This method has dozens if not hundreds of documented cases of people who have both succeeded and failed (combined, obviously more successes, but nearly all fails are interruptions). Also, nearly everyone who survived SN say that it wasn't painful. They remember losing consciousness followed by waking up in the hospital. It's pretty straight forward, the shot of SN is less than 2 ounces. It hits you in 5 minutes, you lose consciousness by 10 minutes and your typically dead after 40 minutes. Unless you can get your hands on Nembutal, SN is easily the best option. I hate puking, but on numerous occasions in my life, I've puked my guts out all night. If I can handle that I can tolerate 1 minute of puking SN/water, before losing consciousness.