If you are serious about obtaining victory, you're going to have to get rid of any and all access that you may have to porn. Even if it means getting rid of your internet or cable connection, any dvd's or magazines that contain racy content, and (the hardest of all) doing your best to stay away from places where there are lots of girls who dress to get attention. Finding a trustworthy accountability partner might help as well.
Regardless, you can't kick this thing by yourself seeing as you are your own worst enemy in this situation. I would know.
Only God can deliver you from it. I strongly recommend doing a deep study on biblical consecration and sanctification. Sanctification is the means in which God cleans us up. Consecration is preparation on our behalf, cutting the cord of anything that might tempt us to fall back into temptation.
1st Corinthians 10:13 "No temptation has overtaken you except what is common to mankind. And God is faithful; he will not let you be tempted beyond what you can bear. But when you are tempted, he will also provide a way out so that you can endure it."
2 Peter 1:3-4 "His divine power has given us everything we need for life and godliness through our knowledge of him who called us by his own glory and goodness. Through these he has given us his very great and precious promises, so that through them you may participate in the divine nature and escape the corruption in the world caused by evil desires."