I dealt with pornography for about 2 and a half years. It was during a dark time in my life that I started to get into it, and the only thing that broke my addiction was my realization that it was severely hindering my relationship with God. Often times I didn't even feel like praying because I knew what I was doing was wrong. Thankfully, I've been porn free since August 2011, and although the temptation is still there at times, it's much more easy to resist because I'm focused on God and I want to serve him.
Like other people said, get an accountability partner. Also, realize that what you're doing is not good in God's eyes. That second thing was what truly motivated me to get out of this habit, and I was able to overcome it by the grace of God.
One thing you should pray about and put effort towards once you are out of this habit is keeping your mind pure. I still have a LONG way to go when it comes to keeping my mind pure, but here is something I have done that has helped me. This may help you as well. As you know, media (especially the internet) is loaded with tempting material. Often times we can run across these things unintentionally, and this can often lead people into sinful habits. Whenever you run across these things, make sure to not let them stick in your mind, and get away from them as soon as you can. In other words, if you're watching a movie and it has an explicit sex scene, turn away and think about something else until that scene is over. If you're on the internet and you run across a tempting picture, scroll away from it or get off the page if you can. Then, delete that page from your browsing history so you can't go back to it. Something I've also started doing is "unliking" facebook groups that frequently post risque pictures.
I know it's a hard habit to break, with the help of God and your other loved ones, you can get out of it. As time goes on and you start to purify your thoughts, it'll become easier to resist temptation! I'll be sure to pray for you!