I love couponing and save tons of money doing so. But a few factors work in my favor:
1. I live in an area that has numerous grocery stores, drugstores, and discount stores all extremely close to me, or on my way to and from work. So I can easily go to wherever I see an excellent buy without spending extra money on gas and defeating the purpose.
2. All grocery stores around here double coupons. One of the drugstores allows you to use their store discount card, PLUS add coupons for those already discounted items. I will sometimes get things I need for free that way.
3. If I do say so myself, I'm exceptionally good with numbers. When I'm at the store, I can quickly compute what I'll be paying per ounce or per serving or whatever when I apply the sale price and the doubled coupon, and then compare it with what I'd pay by buying the store brand instead.
4. I'm also very competitive. Couponing is like my chance to "beat the system" by getting my groceries and essentials for a fraction of the sticker price. lol
I also exercise a few rules in my couponing:
1. When the weekend paper comes, I sit down with the flyers and my coupons. I make a list for each store I find good deals in, and paperclip the coupons and the list to those flyers. That's what I take to the store. I stick to my list at the store.
2. I don't buy items I wouldn't ordinarily buy just because there's a great deal. However, sometimes I've been able to get special treats or try new things because I can get them for free by coupling a great sale with a good coupon.
3. I'm willing to "stockpile" items when I can get a killer good deal. That way if an item doesn't come up for a super price for a long time, I've got it covered in between. I'm obviously careful with anything that has an expiration date.
4. My target is to discount all groceries and essentials by 60-75%, if not more. I'm usually not satisfied with merely half price. (Miserly, ain't I?) Things don't always work out that way when I have to get something and there's not a sale. But that's my target, and I do reach it a surprising amount of the time.
It may sound very time-consuming, but it's not bad at all. Guess I've got my system down.

Besides what I buy for myself, I also pick up many items for my sister and family. I've become very familiar with what they eat and use, so that I can watch for irresistible deals for them too. They appreciate the cheap prices, and are glad to pay me back. It's a fun and easy way to help them out.
So that's my story. Sorry it's so long. It's probably WAYYYYYY more than you really wanted to know, but maybe a couple thoughts will help someone.