Research

One of the most important parts of The Shopping Diet is doing your research.

For example, let's say you're looking for a green trench coat for spring. You know you don't want to spend more than $30 on it. You know you want a tie waist and pockets. You know it would look amazing with your new pale yellow scarf.

How do you go about finding this coveted trench?

My advice, per The Shopping Diet, is this:
Do research online. Use Google. Go to your favorite sites. (the ones you religiously shop at online)
Use Amazon and others like it. Search, search, search.
By doing this, a lot of different types will show up. Some different colors, different styles, different prices. You may come up with new ideas for what you want or you may still be stuck on that one fantasy of a coat that's comfortably set in your mind.
By doing research you are exposing yourself to all your options. If you bought the first coat you saw at $45, and found another just like it for $20, wouldn't you be a little dissapointed?

Once you've weighed out your options, you can make an informed decision. You've seen 30 + green trench coats. Which is the one you like best, for the price you want?

By not doing research you are shopping blindly. Nobody likes that, and you shouldn't either.