Not all coupons are created equal -- some double and some don't. Check out the back of the coupon: If it says "do not double," well, you're out of luck. Another, lesser known, way to find out is to look at the coupon's bar code. If it starts with five, it will automatically double at the register. If it's a zero or nine, it probably won't.
In a perfect world, at checkout time all of your coupons would double automatically and you'd sail through. But it isn't always a cakewalk. Sometimes coupons don't double automatically, and not every cashier is an expert on the store's ever-changing procedures. Even if you've verified the store's couponing policy on the phone, it never hurts to bring a printed copy with you. Don't back down if you know you're right, but remember to always be polite and mindful of the shoppers behind you in line.
Hopefully, you'll save enough money in your first double-couponing experience that you'll want to go back for more and perfect your plan of attack. Next time, keep tabs on store sale cycles and strategically use your double coupons on sale items. That's where you'll really get the most bang for your buck.
On the next page, you'll find more information about couponing.