The most effective way I have found to remove a blood stain is to pour hydrogen peroxide on it as soon as possible. Pour a liberal amount directly on the stain, and it will begin to disappear before your eyes with no rubbing necessary.
Do not wash in hot water. This will set the stain and it will never come out. Place in cold water with some liquid detergent and rub it in. Let it set over night and wash in cold water and hang to dry. Repeat is necessary using the same process.
