For those of you who practice bloodletting for any reason - just to put a couple drops on something, to smear it on yourself or others, or to drink it (or have others drink it) or to trade blood with someone, here are some good, common sense, in-depth articles on safety with blood practices. These come from the vampire community, and so are focused on the consumption of blood, but they are still relevant to any bloodletting practice. Even if you’ve been practicing bloodletting for a while, these are worth your time. Be safe. SphynxCatVP and Shortgoth are well-respected, experienced members of the vampire community who we’ve talked to. They give good, down-to-earth advice. But still, we’d say do your own research before practicing bloodletting, and take a class in first aid if you’re able to (or look for other professional, medical advice on the subject). Asking a doctor about it under the excuse that you’ll be practicing BDSM is one way to get advice, depending on where you live.
We hope these help people!
This one is titled Bloodletting Tools, but covers all the basics, too:
https://sphynxcatvp.nocturna.org/articles/sc-tools.html
This one is about sterilization:
https://sphynxcatvp.nocturna.org/articles/shortgoth-sterilize.html
And one about blades:
https://sphynxcatvp.nocturna.org/articles/shortgoth-blades.html
This is only mentioned in passing in the articles, but having visible or repetitive scars can prevent someone from getting proper medical treatment, and instead be passed off as an attention seeker. This is why it’s important to address scarring, aside from the aesthetics of it, and the possibility of scar tissue growing out of control (becoming a keloid) or becoming cancerous. In general, if you must have scars (or in case you mess up and cause a scar without meaning to), it’s best to choose the area wisely - away from where a doctor would be checking regularly, such as outer extremities like face, neck, hands, forearms, feet and calves (but if you’re cutting your core, be very careful about it going wrong and possible blood loss). You could also try to make the wound look natural (which means it will be more likely to scar if isn’t a clean cut, as far as we’re aware?), and not cluster them together, or only do a pinprick instead of a slash. Etc. We recall that back when we had a massive burn scar, our doctor recommended slathering vitamin E to help reduce it, but we never tried it, and upon Googling it, it seems people go both ways about whether that actually works or not.
Also best to be up to date on your tetanus shot before trying anything. It’s recommended by medical professionals to get a booster every 10 years, but it’s also suggested to get a booster every time you get a questionable puncture wound; obviously that isn’t practical for someone who practices bloodletting. We’ve heard every 5 years or so (didn’t hear this from a doctor, so use your best judgement) is good with regular bloodletting, just to be safe, and it’s unlikely your doctor will question it then. If you were going in every other week to get a shot, though, that might raise some eyebrows…
Take care of yourselves, be educated, be careful, but do what you need to do and have fun. 
And don’t ask us personally for advice on this, because we’re dumbasses who use our teeth for cutting… don’t be like us. It causes big, nasty wounds with a huge mess and a ton of painful bruising. That said, we don’t brush our teeth immediately before biting (bleeding gums are dangerous for both parties), we only swish with alcohol mouthwash. But seriously, use a tool, it’s just better. We speak from plenty of experience. And that way you have more chance to use your needle/blade/etc as a conductor for energy, anyway. Could do a little more energy manipulation or magick in the process that way, we would think.
If anyone has any questions that aren’t answered in those articles, we can look around and see what we can find, if you want us to; but be sure to do your own research, too. And if anyone else has advice, feel free to post it below.