New coupons are released daily. Every month the biggest coupon release day is the 1st of the Month. Also, usually around the 15th is another big coupon release day. To learn the ins and out of couponing, go to this link for more information. There is also youtube videos to help explain couponing, HERE. Also, the Coupon Database will help you navigate through all the available coupons and to search for specific coupons.
List of Coupon Sites:
7.) Procter & Gamble
8.) Betty Crocker
15.) Recyclebank (earn points to redeem for high value coupons)