Coupon Value

I love it when I get "free money" coupons in the mail. I'm sure the stores figure you'll spend more if they can get you there. But the key is to stick to the coupon value when I go shopping.
For instance, I got a "$10 off $10 or more" coupon. So I went to the store and looked at several things on sale, some for less than $10 and some for a few dollars more. But I kept looking around and I found a little jacket, which I had tried on months ago when it was full price. It was marked down to $10. So I used my coupon and got it for NOTHING!!!