It depends on why you were sacked! You could start by doing some voluntary work to get a good reference and some different work experience, or go to college to retrain to better your prospects, or sign on with a temping agency. Learn from this valuable (but expensive) lesson and try not to let yourself down again.
Sit down and think hard about the reasons why. If it is unreasonable, then let it go, it's not worth taking with you to the next role. If there is some truth, think about strategies that will stop it from happening again.
See it as a learning experience, and don't hold grudges, even if you have been wronged.
Remember when one door closes another opens.
I've been sacked and whilst it felt like the worst thing at the time, I went on to bigger and better things and realise that where I was, wasn't the right place for me.