I don't know your particular variaty of self harming or what you, personally, get out of it, but there are things you can do to make things a bit easer on yourself. Here are a few self help techniques....
Get an elastic band (not so tight it cuts off circualtion tho...), put it on your wrist and ping it. It stings but does no permanant damage (so long as you follow the rule with it not being too tight).
Run an ice cube up your arm - simulates a knife.
Invest in a punchbag, you can get the inflatable ones very cheaply on eBay - cheaper than Argos including postage. Hit it. You could also punch cushions, but they don't fall over in such a satisfying manner.
Go to a fete that has a broken crockery stall, break some crockery! If you have any old terracotta pots, break them up for crocks! Rip up thick newspapers.
Do something physical - swim, gym, run, cycle.
Have a good scream. However, screaming can disturb the neighbours :shock: :roll: so you need to be a bit choosy where you do it. In the film Cabaret she used a railway line with a train. There is a roundabout near where I live that is accessed by an underpass. It is busy 24/7, but very isolated - no one can hear you scream there.
Lots of poeple self harm in all sorts of ways

For some it stays low level, for others it escalates. Find someone to talk to. Take a look at the Mental Health Foundation website and the MIND website. They both have good info for self harmers. If you feel desperate, call the Samaritans 08457 90 90 90, you don't have to be suicidal to call them.