From what I know:
It is necessary to cut specific areas of the body, those that make the most blood, and being in a bathtub to avoid healing, anticoagulant medication to thin the blood can help as well as sleeping pills.
I've heard about a person who had stabbed his heart, he must have had a lot of courage and be sure not to miss...
In addition to the fact that these methods are particularly hard, they are difficult to bear for those who find the corpse.
So I don't recommend you doing it, take a look at the night-night method instead, it's cheap even if it's not the best.
Best wishes, I hope you'll find the peace you're wanting