Hey. A necktie is generally not recommended. Usually people go with rope. Neckties and belts seem to snap quite often for people.
I'm here if you need to talk at all. I wish you happiness.
Edit : Like not-2-b-the-answer said, robbin Williams did use a belt...Generally if you're on your knees leaning forwards against the door, the weight on the belt/rope is much less than if you're back is against it in the sitting position, or if you're standing up. The kneeling facing the door position is said to usually not be good.
Please think long and hard about this before attempting. Be very careful. Ensure you're alone for an hour or more if possible(from when you pass out) There is high risk of brain damage if you fail(usually due to being "saved" by someone that finds you). I'm talking quadriplegic risk. There was a guy in the uk that had this happen. He couldn't blink or move his eyes for about 2 years. I think that right now he can only blink(maybe move his eyes?). They took a while to realize that he was trying to communicate and had to get an $8,000 communication system. He is in HELL.