Well, the vagina is self cleaning. So, don't be tempted to douche or do anything inside the vagina. That sets yourself up for yeast infections (gunky cottage cheese discharge that itches) or bacterial vaginosis (smells horrific). So, use soap on the outside. You can try some scented soap if it isn't harsh. But again, that's only on the outside. Honestly, I doubt he'll be too worried about anything when in the act.