This article needs to be written out in full, but my summary is the following keys:

1. You are not strong enough to win, so don't try. The greatest men in the bible, Samson (physical), Solomon (intellectual) and David (relational) were not strong enough. The first step to victory is to realise that this isn't a battle you can win on your own. When you are attacked, admit your weakness to God, and confess your need for His strength to overcome this challenge. This understanding of weakness should also guide you in your thoughts, actions and travels -- keep away from sources of temptation!
2. Develop a game plan that will help you. A good start is No Porn's Breaking Pornography Addiction: A Plan for Personal Success
3. Be accountable to someone -- I encourage submitting yourselve to a couple of people you can trust, along the lines of 'Seven Questions to ask in accountability groups' (need to find these!). If you can't bring yourself to talk to someone you know, go to Porn Prayer Support, 'a prayer group that deals with lust of the flesh in all its forms.'