Three important steps.
Take the sharpest knife you can find. Grab a beautiful, long, steely weapon. My eyes gleam brightly.
Place your victim, sleeping or unconscious, and keep quiet. I'm very lucky. She's sound asleep. Can't see much in the dark.
Stick the knife in your choice of a body part. I choose the heart. The heart I never had.
Now she's shouting. People are coming.
I'm still. Silent.
*Four* important steps.
Run for your life if it does not work.