I think for everyone the questions are different. For me it's the following:
1. Did I try everything I possibly or willingly could to improve my situation? If yes, that is one answer.
2. How likely is my life going to change given my resources, support, and will? If the answer is low to none, that is another answer.
3. How will my future objectively look if I keep on this way? If suffering is a dominant theme, there is another answer.
4. Has my suffering far outweighed my experiences of peace or pleasure? In other words, is your quality of life chronically low to none? If yes, another answer.
5. Do I still have any attachments left in this world? Whether food, sex, people, hobbies? If no, another answer.
6. Am I at peace with my life, including my accomplishments, mistakes, traumas? If yes, there's another answer.
7. Am I prepared for death, whether it's nothing or an afterlife? Am I ok with non-existence? If yes, another answer.
8. Have I let go of any feelings of guilt as a result of this decision? If yes, another answer.
9. Do I have a method and plan that is well thought out and reliable? Can I create the right conditions to lessen the risk of failure? If yes then another answer.
10. Am I emotionally ready to go through with this? If yes, then I'm ready.