Becoming an Extreme Couponer?

I am on my way to becoming an extreme couponer. I already have my homemade organizer and LOVE IT!! But I am needing advice on getting more coupons, and any other advice I can get. I have family members giving me their mailers that they dont use, and am getting them out of the paper. Does anyone know of any websites that actually mail out FREE coupons? Neither of the two stores in my town accept printed coupons. I have been searching all over the internet but cant seem to find any. Any advice on couponing would be helpful. :)