One of my advice to be aware of the promotion of your favorite brands is to sign up for the e-mails. You’re the first ones to know about sales so you can get better deals.
I know it can be annoying to receive emails everyday so I’ll suggest to create a special account for the newsletters. This way, you can only look into this email box when you are looking for something and not be tempting by the everyday “attractive” deals.
I have also just discovered this application recently called Coupon Sherpa available in the Itunes store for free. This app got hundreds of in-store coupons for your fave retailers and restaurants. You just have to present the coupon from your phone and the cashier will scan it.