ECB's are the reward fo shopping smart at CVS. If you're new to the game, you'll have to initially pay some OOP to get started. Study the weeks featured ad, choose the items that will give you ECB's back. Ideally, also use Q's on them for more savings. You'll have to pay out of pocket the first few times, but you'll be rewarded with your first ECB's to get things rolling. Once you begin building up your stash, you can go back again and again, rolling your ECB's on the next deal, and the next....always concentrating on the ones that will give you the most ECB's for the littlest possible OOP.
CVS is a good place to start. You do have a Rewards card, right? If not, get one on your next visit.
And be sure to keep your eye on this site, as well as some other great blogs-they have the deals laid our for you-making for some very rewarding shopping ventures. PM me and I'll be glad to tell you the names of my favs.