The first element of a successful window treatment of any type is choosing a suitable fabric, or vice versa, choosing the right treatment for a chosen fabric. When the designer fails to consider the appropriateness of the pairing of a treatment and a fabric, the results can range from disappointing to tortured, even if the fabric is super-high-end-awesome and the treatment is stunningly original. Expertise in evaluating a fabric's appropriateness is acquired mostly through a great deal of exposure to fabrics and some understanding of the structure of a treatment. Often the swatch in a sample book is insufficient for judging; sometimes not even a memo sample is enough. When a lot of money is going to be spent on fabric, it's a good investment to order actual yardage and make a mock-up to be truly certain that the right choices are being made and that the fabric is going to perform as expected. That mock-up can become a workroom sample, or a treatment in, say, the designer's sister's powder room, or cut up for pillows.