Treat the blood stain as quickly as possible, giving it as little chance to set as possible. Do NOT rinse with hot water, which will only set the blood stain. Instead, flush blood with cold water and then soak in cold water for a half hour. Apply a small amount of hydrogen peroxide to the stain directly to treat stubborn stains.
Scrape off all dried blood. Create a soaking solution of cool water and detergent, and soak for at least 30 minutes. After soaking, treat stain with stain removal spray and launder in cold water.