Claire and I aren't much on Halloween. In fact, in past years, we have decorated our windows with fall items along with large, colorful letters spelling out, respectively, "Happy Reformation Day - October 31" and "Have a Wonderful All Saints Day -- November 1."
But for those of you who must deal with costumes for parties and trick or treat outings (especially for those of you trying to escape the immodest and inappropriate costumes being sold for girls), I couldn't suggest a better source of information and assistance than Kathryn's post over at Suitable for Mixed Company.