This time of year, a lot of photographers are using coupons to encourage sales for the holidays. But if you haven't used coupons before, there are some pitfalls you should be aware of:
Coupon not enabled for the gallery: Some photographers seem to think that if they set up a coupon (or any discount, for that matter) in a pricesheet, it is automatically applicable to any gallery using that pricesheet. That isn't the case. You need to go to the gallery selection screen for the coupon and pick the galleries you want the coupon to work for. Make sure you use the "Inherit" box to tag all the subgalleries, and then click on the names of the parent galleries (the ones with the asterisk next to them) to verify that all the subgalleries are tagged the way you want.
Gallery uses a different pricesheet than the coupon: Just because you can select any gallery for the coupon , doesn't mean that the coupon will automatically work when someone orders from that gallery. The gallery also has to use the same pricesheet that contains the coupon. This is necessary because the products in each pricesheet are considered unique. A 4x6 in your "Sports" pricesheet and a 4x6 in your "Wedding" pricesheet are two totally different products, at least as far as ExposureManager is concerned. So a coupon set up to work with one pricesheet's products will not work for the products in another pricesheet. There is a work-around of sorts for this issue: if you do not check any products for the coupon, then the coupon will apply to all products, regardless of which pricesheet they are on.
Coupon set up outside of a pricesheet: This is a variation on the different pricesheet problem. Some long-time ExposureManager customers still have access to the coupon interface from prior to the introduction of pricesheets. They think that they can set up a coupon using that interface and have it apply to all their galleries, even those using pricesheets. This has the same problem as using a different pricesheet: the non-pricesheet products are separate and different from those in the pricesheets, and if specific products are selected for the coupon, it won't work.
Coupon conflicting with other discounts: Only one discount can be applied to any one item in an order. In addition, coupons have the lowest priority, because the coupon code gets entered after the other discounts have been applied. This is a particular problem with volume discounts, which tend to be applied to an entire order. So if you decide to offer a 15% off volume discount for the holidays, your customers will suddenly find that their coupons no longer work.
Multiple coupons with the same code: Some photographers think they can get around the different pricesheet issue by setting up the same coupon code in all of their pricesheets. Their logic is that the coupon code should then work regardless of which gallery and which pricesheet the customer is using. Unfortunately it doesn't work that way. When the system finds a matching coupon code, it then checks if it is applicable to the products being ordered. If the coupon doesn't apply, the system doesn't check the rest of the coupon codes to find another match. You should always make your coupon codes unique to avoid a problem.
Expiration date: There's always someone who will be trying to order at 11:55 pm on the last day the coupon is good for. And the coupon isn't going to work for them... When you set the expiration date for a coupon, the coupon expires at 12:01 AM Pacific Time on the expiration date. So if you're on the East Coast, the coupon will be good until 3 AM. That is why ExposureManager recommends setting the expiration date to one day later than the date you advertise to your customers.
Finally, one of the things ExposureManager can't stress enough: TEST YOUR COUPONS AND DISCOUNTS. And not just for a simple, minimum order, case. Try to come up with an extreme example (like a $900 order, or 30 copies of one print) and make sure things work the way you want them to.
EDIT: Added the item about coupons conflicting with other discounts