My tips is don't believe what you see on TV
I am and avid Q users, but that show is called EXTREME for a reason. Many of them state that this is the largest transaction they have ever made, and that they've never made such large orders before.
Look at your weekly circuilar for the stores you shop at most, mark what is on sale for items that you use and then try and match up as many Q's as possible to save more on those items.
I have purchase Q's on Ebay before in lots. But that was mainly when the boys were in diapers and I could combine a sale and a coupon for better savings.
The biggest thing is have a menu and a list when you go shopping. Don't go in the store having no idea what you're going to make with your groceries or an idea of what you're going to be getting. A lot of times, you have the groceries for X meal, but you don't "see" them, because you didn't plan.