I've used Cartwheel by Target, it can be accessed through the App or Facebook, but I prefer to print them since I can never remember to open the app at checkout. You can definitely save money, but it can get a little complicated (for me at least) since you can combine the Cartwheel, a Target Printable Coupon or a Target Mobile Coupon, a Manufacturer coupon and by using your Target Red Card for the extra 5% savings.
This is a website I use for all the Target Coupon Matchups (I'm not affiliated), I'm just glad someone can match the sales with the available coupons - TotallyTarget.com. The FAQ section is very helpful.