I prepare, to gain a sense of control at the start of it.
Then I do the SI in relatively the same order until I feel relief. Sometimes the first go around wasn't enough so I'll do it again. Ill feel over the wound to feel satisfaction and bury the feeling that caused me to react that way.
Move on and act like it isn't there, until the next time when I see the past marks again.
On occasion I will try to stop a new mark from being made by running my hand over the old scars like I want to remember the act without acting again. Sometimes it works, sometimes it doesn't.