Blood in rituals and general human sacrifices in occult rituals, it’s the stuff of Hollywood mostly. The question is, is it necessary or beneficial to an occultist to use this within rituals or spirit work? The answer is, simply put: N-O.
My own Patron, Lord Samael, did not need or want blood offerings when the idea crossed my head and I took a look to see if it would be a good idea to offer Him some of my blood in a vial for example. Answer again is NO. There is nothing special in blood, nor does it have any exceptional properties that will accelerate a working. This is a misconception that started somewhere in time. Most magicians will tell you too that this is impractical and spirits have no need for blood, because there’s nothing special about it in comparison to regularly offered items.
There have been civilizations in the past that were big on this, the Aztecs being one of them. This form of offering was in their case reflecting on their beliefs, but even then it would not be necessary; they thought so, but they were wrong.
This would only be acceptable in my mind in a situation where there’s nothing else that can be offered; no gift, no food or drink…which will be almost never. For more information on blood usage and related from a religious PoV, see here.