I find that I "save money" by simply staying out of stores. If I go in there I start finding things that "I didn't know I needed" until I saw them, so for me that works. YMMV.
When I do go in for something specific I try to focus only on that item and then get out before something else catches my eye. Several years ago I took a class in marketing and it was a bit of an eye-opener. Stores, especially the bigger ones, have people who spend their entire careers studying how to present things in the best light (often literally), the packaging, position on a shelf, or anything else that works. Next time you're in a clothing store for example, cast an analytical eye on the spotlights on the ceilings and walls, and how they're used to brighten the look of the higher-priced items.
In most department stores for example you have to walk around the jewelry and cosmetics displays to get anywhere else in the store because those items are often impulse purchases, and the reason in grocery stores that staples like milk and eggs are in the back. So I try to maintain a conscious awareness that the entire environment is designed to part my money from me, and to not be manipulated by that environment.
