Your arteries are in there, believe me. You probably aren't applying enough pressure because damn survival instinct subconsciously prevents you from squeezing too hard with your own hands.
Carotid arteries run up and down your neck on either side. What you want is the proverbial sweet spot you see in crime shows and movies where attackers "magically" force their victims to pass out in a matter of seconds by compressing the internal and external carotids to block blood flow to the brain.
For me that's slightly above the middle of my neck so that's where the ligature is placed and firmly positioned so it doesn't slide up and down accidentally relieving the pressure.
I had a few "dress rehearsals" and used a heavy bathrobe belt tied with a simple slip knot anchored to my closet rod. I put the belt around the upper middle part of my neck, pulled it as super tight as I dared, and then bent my knees and leaned forward like I was fixing to fall on my face.
Saw white twinkly spots which started to swim and then everything got blurry and dim like looking through a dark scrim. Got lightheaded and came dangerously close to passing out.
All in all it wasn't too painful, except the tightness of the belt, before the light swimmy spots and dizzy darkening kick in. Didn't even feel the need to take a next breath between leaning forward and almost blacking out.