Proper tourniquetes and application:
Material MUST be at least 1" wide. Any thinner, and you are likely to cause more, severe tissue damage by putting too much pressure in a narrow area.
Apply approx 3" above wound (about 4 fingers is a quick, good gauge)
Twist that baby tight... I mean TIGHT. If the patient is awake, they will be calling you every name they know...
As for length of time: (this is almost confusing)
You can throw it on when you need to stop bleeding and then proceed to another life threatening issue. You can later go back to the tourniquet, and if you think it might not be needed, SLOWLY let the tension off and watch for profuse bleeding. If noted, tighten it back up and leave it. If no bleeding, leave the tourniquet in place, just slack and then pack and bandage the injury.
They CAN be left on for quite a long period of time before amputation is a sure thing... I'm talking HOURS... Way more time than you will ever have to wait for help in most circumstances any of us will be in. After 3 hours of it being on, you are NOT to attempt to release it as there is a high risk of embolism due to clotted blood in the extremity moving up once the TQ is released.
There is arguments as to how long is too long, so I can't give you guys an answer, but thems the basics.