I've done testing (stupidly) with an actual combat tourniquet, a CAT GEN 7, I believe. Those are great because there's a mechanism (basically a clip and velcro) to keep the windlass in place, so it won't come off. Only thing is, they are way more expensive then they have any right to be, (it cost me 40 € for basically a piece of plastic and velcro) so with that price you could probably consider bying the necessary stuff for the SN method.
I recommend this method. It's good. It can feel finicky at first, and the device can feel awkward, but stick (pun) with it and it can be very effective. However, do not practice unless with a friend, or you know you want to die and are okay with the idea of dying now. This is a lethal method. Once the dizziness kicks in, you have very little time to back out.
Would you elaborate on this, please? The same pressure is needed to lose consciousness and to die. It isn't possible to go far enough for you to pass out but not so far as to avoid death. What you should worry about, is the windlass coming off, which the combat tourniquet fixes. Alternatively you could use some tape.