I get asked this question frequently. My answer is usually, "from the Sunday paper". However, there are many ways to get coupons.
1) Most coupons are found in the Sunday paper coupon inserts. Every week (except holiday weekends) there is at least one insert, but usually more. This week there are FIVE! I buy 4 copies of the paper each week, but on big weeks I buy more. If I know about some really high-value coupons coming out, I will buy more. This week I bought 6 copies - I've got a lot of coupon cutting to do!
2) Peelies, Blinkies and Tear-Pads. What? Let me explain.
Peelies are those sticky coupons attached directly to some products on the shelves. Like finding gold! Keep your eyes open for these.
Blinkies are the coupons that pop out of those blinking boxes near the product they're for. Most of the time they say "Do not double", which is a bummer, but some are worth collecting. Look for high-value ones and keep them on hand for those upcoming sales.
Tear-Pad coupons are found all throughout the stores in various locations (sometimes even in the produce section) on tear-pads. Take a couple if they're for products you use - you may find a sale in the future where they'll come in handy.
3) In-Store Coupon Books
You can find these in all sorts of places throughout some stores. Fred Meyer has one called "Naturally Preferred" and it's usually located in or near the health foods section. It's free and it comes out once a month. This month you'll find the following coupons in it:
$1/1 ANY Kashi organic cereal (expires 10/31/09)
$1/1 ANY Annie Chun's item (expires 3/31/10)
$1/2 ANY 2 Amy's products (expires 11/30/09)
$1/2 ANY 2 Simply Organic spices or grinders (expires 3/31/10)
(the above coupons are manufacturer coupons and are valid at any retail store)
25% off Nutrition Now Kids' Rhino Supplements (first 2)
$1/1 Knudsen Just Juice 32 oz. (first 2)
$0.50/1 Naturally Preferred Organic Veggies or Berries 10 oz. (first 4)
$0.50/1 Naturally Preferred Brown or White Cage Free Eggs dozen (first 4)
Cliff Twisted Fruit or Z Bars 2/$1 (first 10)
Country Choice Organic Cookies or Oatmeal 2/$5 (first 4)
$0.50/1 Naturally Preferred 1/2 Gallon Organic Milk (first 2)
25% off Naturally Preferred Herbal Supplements (first 2)
(the above coupons are Fred Meyer coupons)
A similar book is available at Thriftway and has similar manufacturer coupons in it. I found it in the produce section. Walgreens has their own coupon leaflet each month (not the weekly circular), as well as sometimes a pharmacy booklet. I usually just go to the pharmacy counter and ask if they have a new one. Walgreens has one right now called "Healthy Savings" and it is full of health-related coupons in it. Don't forget that you can "stack" these store coupons with manufacturer coupons on the same item. (i.e. Walgreens coupon for $2/1 Triaminic Thin Strips from the Healthy Savings booklet stacked with manufacturer coupon for $1.50/1 Thin Strips makes for FREE product at Walgreens starting tomorrow! Read about it in It's Hip 1 Save's Walgreens post.)
Many times a manufacturer will send samples to you for free and include high-value coupons with it. Often I will sign up for a sample simply to get the coupons.
5) Coupon Booklets Directly From the Manufacturer
As I've posted before, you can often sign up for a booklet full of coupons sent directly from the manufacturer. Proctor & Gamble puts one out at least 3 times a year called Home Made Simple. You can order one right now by signing up here (thanks, Saving with Shellie!).
6) In the Mail
I've tried this and it works! Send an e-mail to a company and request coupons from them! Go to their website and click on their "Contact Us" link. Send a simple e-mail with a comment on their products or a reason why you'd like some coupons. I've written to several companies recently and received coupons for cents-off specific products and even coupons for free products! Check out this post by Nicole's Nickles. She gives links to many companies to make it easy for you!
You can print off coupons at thousands of websites on the internet. Many are found on product websites, many can be found on coupon websites like coupons.com and redplum.com. If you want to know if there is a specific coupon available, check out hotcouponworld.com. They have a coupon database where you can locate practically any coupon available!
As you can see, it pays to keep your eyes open! Don't be shy about taking coupons you find! You may not need them right away, but you never know when a great sale may come around when you'll be happy you have them.