Besides printable coupons, there are lots of other ways to find coupons without buying the paper.
Look down the aisles of your stores for the little red blinking coupon machines. Grab a few. Save them for a good deal. They are manufacturer coupons, so they can be used at any store.
Front of the Store
I mentioned a while back that I found a stack of coupons by the ads at Meijer for completely free butter spread. You'll find all sorts of coupon books if you keep your eyes peeled.
If your store has a sample day (Saturday for most stores), chances are they are passing out coupons with the featured items. I grabbed some last week at Meijer.
Even if you don't receive the newspaper, you can probably get your hands on one. Talk to your neighbors and friends who get the newspaper. Ask if they use the coupon inserts. If they don't, then ask if you can have it. I would guess that most people who take the paper are not avid couponers and would have no problem giving it up.
In or On Packages
Last year there was an sale on Quaker granola bars for $1 a box. Printed on the inside the box, there was a coupon for $1 off your next box. You better believe that I bought a bunch, brought them home, cut up the boxes, then went back for more (and more, and more) for free.
The last 2 times I was in Walgreens, I found some stray coupons that someone left in a cart. Seriously. It was like the coupon fairy had sprinkled my cart.