I don't think it necessarily matters how tight you have your ligature/tourniquet. Just as long as it's slightly below the jaw and above the adam's apple. As long as it's above the adam's apple and slightly below the jaw you will be able to breathe regardless of how tight it is.
The pics I sent are some bad examples but the sweet spot (at least for me) is in this little area between the sternocleimastoid and the wind pipe. It's in the carotid triangle, right under the jaw as high up on the neck as possible. It's a little closer to the ear, if not then a little closer to the wind pipe but it's right in that area. It should a blob. Keep looking in that general area.
IMPORTANT: don't put pressure on it. You can check your pulse to see where it is but don't try to make yourself faint. It will give you brain problems. Only do this method when you are ABSOLUTELY sure you are ready to die.
If you're gonna kill yourself with the korean method thing I recommend you you buy a TIME tourniquet from amazon. If not then use this guide to make your own (it's a little hard to follow):
https://thephilsopherprophetoftheed...tc-optimal-euthenasia-strategy-and-device.pdf