> What not to do...
TL;DR: Do not copy/paste. Do not suggest a suicide hotline. Don't lie. Don't treat them like a baby. Don't try a quick-fix.
Suicidal people are encouraged to be open, and talk about their suicidality---it helps. But the instant you do, people begin acting very weird. Anyway, here's my tips:
Do not copy/paste from a script.