Articles like this are helpful for some ideas. However I disagree with the methodology used(mandatory shopping list, cash only...), although maybe it works for impulsive people.

It's good to have a shopping list and to be conscious of your wealth/income. However in my opinion the best tool is have a set of principles.

Thinking only about money will often fail you. It's better to think: Given my requirements what is the most cost effective product? You probably don't want to waste time having to fix bad quality items, or going to work with a dirty shirt because your detergent is worthless. Or buying a cheap thing to realize that it was crap and having to buy the expensive product later on anyways(after having lost the money you put on the cheap thing).

On some products, like tools or a car, you should ask yourself: Will this product ever let me down? How long will it last? A lifetime? Keep in mind that pricey products can be good deals too.

On commodity goods spend less, on everything else spend smarter.