Cleaning blood from carpet is not an easy task, mainly because of oxidation effect from blood and that after it will dry it will bind with carpet fabric. That is why it is necessary to moisture carpet before you can actually start working with carpet. I had a pleasure of working with this type of stain for some time and I can say that it takes some time to get them out of carpet especially if you are dealing with big stains and wool carpets.
I do like to clean this sort of carpets as they produce nice before and after photos 🙂 however it may not be that much fun if you need to do it yourself and you don’t have commercial interest in front of you.
First stages for you to undertake is to moisture the stain, if you have under your disposal some ammonia it will be greatly beneficial as it will help to soften your stain and then you can extract it with washing carpet cleaner. Using baking soda will be good as well, however baking soda will be most beneficial to clean afterwords and to extract any moisture out of carpet that will be great way to get rid of smell along the way.
I love using ammonia and some other antibacterial chemicals that add this nice super kill to bacterial development.
Good luck for everybody dealing with those stains.