"Suicide in an acceptable manner" sounds as like an oxymoron.
Why would you care that it's "acceptable" by society which you will no longer take part of ? If your concern is pain, then perhaps that is your mind telling you NOT to end your life and seek therapy instead.
Assisted suicide only makes sense in situations where the person is in extreme chronic pain and no palliative care or treatment can be provided, which is rather rare.
We should not be encouraging or celebrating suicide, it takes away innocent lives, especially younger ones. If you ask the survivors, many of them are glad they didn't go through with it.