I think I read this in Intro to the Devout Life, but it occurred to me that its something I've unconsciously been doing lately which has helped me.
If you are struggling with a particular sin, become outspoken against that sin. For example, if you struggle with pornography, become an anti-porn activist. In this way, you can help build your identity around being against something--falling into it will be repulsive to you because of the cognitive dissonance (a conflict between your belief and desires or actions) as well as your desire to be Godly. Perhaps this is one reason that support groups are effective--just as we learn best when we teach others, perhaps we can learn to best resist a sin when we help others to do so.
I'd love to hear any other thoughts about this, particularly ways this can be used to combat different types of sin. Can we ever talk too much about resisting sin? I doubt it!