If you have get blood on clothing and you want to avoid stains, soaking overnight in lukewarm water with a bit of hydrogen peroxide generally prevent stains. There's still blood in the morning, add more hydrogen peroxide and soak again.
If you don't have hydrogen peroxide handy, you can put salt directly on the blood spot and scrub with a small amount of water. This doesn't work quite as well but definitely helps.
There are lots of accidents and #nosebleeds in our family, since we have a couple of very active kids. This has saved us a lot of stains. My partner told me they didn't know this untill I told them, so I figure I'd share with anyone else who doesn't know. Hope this finds someone who needs it!
@Hex hydrogen peroxide got henna stains out of my white top. do recommend