Where should you apply tourniquet when drawing blood?

When drawing blood, the tourniquet should be applied around the upper arm, approximately 3-4 inches above the site where the needle will be inserted. It should be tight enough to impede venous blood flow but not so tight that it cuts off arterial flow. This helps to engorge the veins, making them more prominent and easier to access for venipuncture. The tourniquet should be removed as soon as the needle is inserted to minimize discomfort and prevent complications.