Recently it's something I've been looking into. I love casting te shells out I tote mat and watching to see what I've been told. My method is base solely on numbers. I do have specific significant rules though. Should a cowrie land on its side, the spirits of the dead are trying to converse with you. Should a closed shell land atop an open shell or vice versa, someone is working magic against you. Should all the shells be closed, there is no answer to be given. It's a blank slate. All shells up mean the possibilities are quite literally endless.
It's far from a perfect system, but I'm working on it. So far I've been using (loosely) the number system used in the Tarot. Although all Tarot cards have specific meanings, the numbers they fall under all share similar qualities. One is a new beginning; the start, two is balance and partnership, things of that nature. It's going to require a lot of studying to fully understand the cowries. However, it's definitely something I want to fully develop. If you've ever used cowrie shells for divination I'd love to hear your methods. If you've never used them, I'd love to year your thoughts.