good idea or not and will it hurt more because its on my wrist

I have a tattoo on each wrist, on the inside (palm-of-the-hand side). They didn't hurt much at all.

Since there is a movement called "To Write Love On Her Arms" which is dedicated to helping cutters, I would think a tattoo of the word "love" -- or simply a picture of a heart -- would be quite effective. When you see it, let it remind you that you love yourself too much to cut yourself. I hope it works.