As you mention substance use is an option. Alcohol, benzos, opioids... All these things dull pain, but also have the effect of reducing consciousness. The risk here is that if you are not fully conscious you might make an error in your method and fail. My advice would be that it should be fine if you were to take a few shots to get tipsy or the equivalent with other meds, but don't take so much that you feel drunk/"out of it" and unable to complete the method.
Other things people have suggested is padding the noose around your neck. This can even be done with a t-shirt or towel. It will help reduce friction. I plan to roll up a t-shirt so that it is thickest over my carotid arteries, and thus it will help compress them and hopefully make the hanging more peaceful (although I am still testing my method).
I believe on the hanging megathread it is also suggested that you may lubricate the ligature to make it close/tighten around your neck more easily.
Ultimately it will most likely not be comfortable. Even if you target pressure on the carotids or intoxicate yourself there will still likely be some pressure on your airway, and nothing is as panicking as the feeling of being unable to breath or strangulated. Due to this it's probably a good idea to "practice" a few times and get used to the feeling. Recently saw a video someone shared on this site of an NSFW/fetish video of a woman being hanged and she appeared to pass out within 10 seconds. She was flailing for some time, but from what I could tell this seemed unintentional and probably due to the confusion that sets in with cerebral hypoxia.
