Cutting is rather frightening. But, as of late, I do know what it feels like to want to go to that point. Although, instead of blood, I'm looking forward to blacking out for periods of time. Asphyxiation isn't funny, kids.
I resist though, even if my life is crud at the moment. I don't really think a person should act upon those thoughts, even if I can truly understand why they would be thinking them. My advice to you; refrain and find alternatives. Talking or venting can take your mind off of physically doing something. Pretty much focusing on any hobby can help, or finding something to keep you busy. One wrong slice and you'll be in the hospital. Or lose use of your hand or whatever limb you're cutting.
Also, think very carefully about how others who know you would react to you hurting yourself. I'm terrified of scarring my sister like that. I think every person has somebody willing to smack a razor from their hand, they just need to talk to them.