When it comes to safety; As long as you are mindful of what you are doing it and how, it can be made a safe part of your practice. Just use appropriate sense.
For example, pay attention to what the spell is asking for and consider the logical consequences. Anointing something with a drop of blood, for example, is sensible and could be expected to not be harmful. While something calling for you to slice your palm open or fill a chalice with blood is both dangerous and unnecessary as there are many risks of lasting damage. Not to mention scarring, potential infection, loss of use of the hand, and poor healing because the wound would be difficult to keep closed.
As for how to incorporate blood into a working, consider what blood is and represents; Blood is made by your body to carry oxygen throughout your physical self, fueling your life. Blood carries your DNA, the blueprint of what makes you, well, you. Historically 'blood' represents lineage and family, the history of your bloodline for a long time largely defined your station and quality within the eyes of society. It also represents life itself.
So, putting it all together, blood represents yourself in its entirety, Body and soul, past (family) present (you) and future (potential new generations of your bloodline/genes).
So you would incorporate blood into your working when you want to literally put the whole of yourself into the effort. To me it is a representation of total commitment and also a complete interweaving or binding of yourself and your energy and effort towards your goal. A literal putting of yourself into your work.
So consider when and where you would want to apply those symbols into your working. And only do it, like with anything else, when it is appropriate and purposeful. Using blood for blood's sake, or even worse for the dramatics/edge factor, is wasteful at best and unwise or harmful at worst.
And considering that blood is itself a symbol all it has to do is be present. No quantity beyond a visible drop should ever be needed or called for. Which also means the tool involved to implement it is able to be likewise simple. The tip of a finger and a sterile lancet is all you should need. Ever. And you can get them from any drug store for cheap as single-use blades or even in a refill-able spring-loaded cartridge so you don't stab yourself too hard with it. Just a click and a little squeeze.
i agree with first replier and frankly blood magic or blood rites are a slippery slope you can do some nasty things with that power.
And depending on preparation like the use runes and runic formulas.
to use runes correctly do much research on the symbols meanings or you can either fail the runic and start over or make the veatta angry and give you misfortune until you break the said material or draw spiteful spirits to your home.
so start small without blood and when the situation demands it try it with blood
(note) blood rites are a big deal this is the most personal part of your spirit and body
so dont use it willy nilly. Skald friend
