In this situation, if you're using your own blood, you have to be very careful and always use sterilized equipment.
Let's say you have a little offering bowl for Hades with his favorite things in it. You can simply prick your finger and let the blood drip into the bowl. You won't need much and you shouldn't use alot. You blood is your life essence.
I wouldn't call it much a sacrifice. More like an offering.