Missy, different stores have different policies and rules. I suggest focusing on one store to get started
I know most have a 4 like coupon per transaction. So sometimes they have like multiple transactions but I can imagine the cashiers must get super annoyed by it and sometimes not allow it.
Also stores like target have their own coupons. You can use a Target coupon combined with a Manufacturer coupon (like the ones you get in the Sunday paper) to get even more of a discount.
LB is a fan of some couponing blogs. Ask her to post em. I've been trying to get into it myself. The most I've gotten was free chapsticks and bread for .19