Even if she had insisted on producing the cards before having orders in hand, I would have recommended leaving most of the cards uncut and temporarily blank inside. This would have allowed flexibility for change based upon future feedback. To this day, I believe she still has enough cards to last her and all her friends and relatives several lifetimes. She did no testing, she created a product that was frozen in a design that wouldn't sell, and she built up inventory far too early. There is another item in the list that deserves special attention.
Most people know the three key words in real estate investment are location, location, and location.
However, I often tell clients that the three key words for success in getting a product to market are test, test, and test. The reason that testing is so important is rather simple. Unfortunately, many people rely on the opinions of friends and relatives versus actual tests on genuine, potential consumers. Friends are a great source for ideas and support, but not for guidance. Knowing that you don't know is one of the keys to your success.