Make sure you’re ready for it. The fact that you’re scared of the word kill kinda shows that you’re not. You’ve gotta be all in on death curses. And you have to know how to hold and direct your power as well. It’s not “instant kill” like in a game, make sure you’re ready for the weight of what happens.
That said, I’ve written my own death curse (worked), asked Glasya-Labolas for help (worked), and asked Forcalor for help (worked). Make sure you know what you’re doing, make sure you’re ready for what happens. Stay protected, keep clear intentions.