Tips on how to determine if those retailer discounts are really worth it. By Carolyn Bigda, Contributing Writer From Kiplinger's Personal Finance, May 2015 Move over, Sunday coupons: Retailers dangle discounts in other ways these days. But to get the deals, you have to give something in return. Here’s our take on when the trade-off is worth it.See Also: 6 Costly Mistakes Target Shoppers Make Become an e-mail subscriber. Worth it, but wait until you’re buying a big-ticket item, says online shopping expert Michelle Madhok. You get a discount of, say, 10% or more, but the coupon is good only once, and only for a limited time. Connect on social media. Worth it for retailers where you shop frequently. By “liking” stores on Facebook or following them on Twitter, you get early access to sales or special discounts. The same goes for downloading a store’s mobile app. For example, Gilt.com, a flash-sale Web site, runs mobile-only sales. Get a store credit card. Not worth it, especially if you carry a balance. The average interest rate for retail cards is 23%, compared with 15% on general-purpose cards. The interest you pay will quickly wipe out the discount of 15% or more you get when you open the card. Instead, use sites such as GiftCardGranny.com to find discounted store gift cards. The savings can be as much as 20% or more.