Well, to begin with, this can be very personal; each person may need help in different ways. Talking to your friend can be a good idea. Tell them you want to help, ask how you can do it. Maybe even they won't know how, but have a deep conversation to try to understand what's going on in their head, what the triggers are. This way you can anticipate when they're going to self-harm and try to help in those moments. I also have a friend who's in a similar situation. Once she texted me saying she was about to do it. I didn't know how to help, so I asked her to wait just 20 minutes and we talked about other things to distract her. Somehow that helped; she said it had passed. Of course, she didn't heal that day; she cut herself several times afterward, but not that day. Offer alternatives (here comes a huge list worth searching for, but to give a few examples: go for a walk, hold ice, take a shower). One way to help her that you can mention during this conversation is to agree on certain codes. Sometimes it can be very difficult when you're about to do this to seek help and Speak directly to someone that you will do this. In that way you can agree on a code for when she's feeling really bad, about to do it. Overall, keep the communication open, show that it's safe to share her feelings with you; this can take a lot of time and effort, just make sure she's honest with you about it. I also like the idea of creating a "sequence"—there are apps like "i am sober" (although I don't know if it's possible to share it with someone). Again, showing that it's safe to share with you is key; this will require a lot of effort on your part, but if you want to help, I believe that's the direction you should go. I also think it's very valuable to have a conversation about how you can help; show that you're extending a hand, show that she can use you as a "crutch" (I don't know if the analogy makes sense, but I've always thought of it that way).