There are actually several ways to save time and money when you shop. It all depends on what you are buying, when you want it, and how much effort you want to put into the process.
The quickest and most effective way to save money on groceries is to learn how to use coupons. This isn't as hard as it sounds, nor as time consuming.
Just buy a Sunday paper each week and save the coupon inserts. Then go to a site such as Couponmom.com. There you can choose the store(s) you shop at, along with a list of their deals. These will also list any coupons which apply and the week they appeared in the paper. I love the site because it includes an ebook which helps you maximize your coupon savings.
If you don't have the time or inclination to clip coupons, you can also buy them for pennies at Couponclppers.com.
If you are buying online, do a little comparison shopping at a site like Shopping.com, which quickly shows you where a bargain is. Depending on the merchant, you may be able to get cashback rewards at websites like Ebates.com. Check out Retailmenot.com, too. they have hundreds of online discount coupons.