Unless, of course, they're actually into that. But then that's their decision, not mine. Whatever. The point is, that when I read the cards, I tell a story. I had this discussion with a fairly famous agent at the last NJSCBWI conference over dinner, and he, surprisingly, was fascinated by the way I described it. I don't read just one card, but try to see how they all connect together.
I tell you this because there are writers who use cards to plot a story. Not me. But I find that reading cards and telling a complete story is really great for flexing my storytelling muscles, finding the one aspect of this card and seeing how it fits into the others that have come up, like fitting puzzled pieces together. Sort of the way that really good stories seem to come together.
I have several decks, but my favorite is the Steampunk Deck. I have a Fairy Tale deck that I also like, but that is harder for me to work with. Who knows why. My favorite thing about the Fairy Tale deck is for me to know the story behind the image (and some are pretty obscure) in order to see why the artist chose it, what part of the story connects to the meaning of that card. Little Match Girl, for example, is the Three of Swords. It's a card of heartache, three swords through a heart. The Little Match Girl is a perfect story to depict heartache (and always makes me cry).
Anyway, if you want to learn to read Tarot to help with your writing, I recommend it. You don't even have to learn the meanings of the cards, if you don't want to. Get a deck with pretty pictures (I recommend ones with actual humans, not Cat People or Dragon or anything) and study the pictures and try to come up with a story that goes along with them. Soon you'll be piecing together all kinds of stuff, and maybe story construction will become easier for you.