If you tend to make impulse buys or just want to save money, try ignoring commercials and not reading the flyers and advertisements in magazines, newspapers and other places. When a commercial comes on while you're watching television, mute the sound or leave the room. When shopping, go directly to the item(s) you are looking for, without browsing or window shopping.
If you don't know that an item exists, you won't want it. If you don't know what you are missing, you won't miss it.