Shop at stores that multiply coupons. Some stores double or triple coupons everyday. Other stores have certain days on which they will multiply manufacturer coupons. Be sure to read the fine print, because some stores just allow a limited number to be multiplied, require a minimum purchase, or only multiply coupons with lower values.
Consider shopping where you can purchase items in bulk. When there is a coupon available, buy essential items. Coupons very rarely last for eternity. Make sure you pay attention to shelf lives of the products. If you have more than one coupon for an item, use them both. You'll save a lot over time.
Purge old or unwanted coupons from your collection routinely. Keeping your coupon stash filled with expired coupons is a waste of time and money since the clutter keeps you from finding the coupons that are most useful to you. Make it a point to clean out expired coupons every week or so.