I have been doing Affirmations as taught in "Feel the Fear and Do it ANyway" for around a year. I think they work to some degree. I certainly think it is worth doing. It's more than just trying to change from the outside in, although certainly that aspect may provide some benefit.
What you are really doing is reinforcing a positive attitude and positive self-talk. I had a chick read mine into a tape that I play to myself. I guess my theory is it will help by providing me with positive feedback from others as well as my efforts to develop better self-talk.
Another thing I have done is taken a survey of traits by females who have known me for at least a few months, I never asked guys to do this because most of my guy friends would probably die laughing
Anyway, aside from learning which areas might need attention, I have learned I am really quite effective in my self-presentation.
I think the affirmations, sedona method, cognitive-behavior therapy, and mediation all have given me something useful. Affirmations by themselves would help, and some recent studies I've read suggest they do, but I personally feel they are best combined with other tools. Women defintely pickup on the fact that you're a guy who has his emotions handled. Emotionally needy men tend to repel women.