hi there, i recently discovered that i want to explore knife and bloodplay with my partner. i apologize if these questions have been asked before, im just looking for answers more specific to my questions :P
i am very unfamiliar with the subject as a whole, so any sources for info would also be very appreciated!

first of all i'm wondering about what the most effective method would be when it comes to covering myself in my own blood. assuming that would be done with a needle, where and how should i have my partner extract the blood from? does it matter? how much can be taken safely? and when it comes to making cuts with a knife, is there a way to prevent scarring or will every cut scar? are there bloodier/less bloody, more painful/less painful areas to cut? are there places i should absolutely avoid with a knife?

also, if anyone has any sort of bloodplay ideas please share! stories are great too, thank you very much!