I originally responded to this thread when it was in the Tarot section. I see it got moved to Oracles (because Oracle decks were mentioned as being used in conjunction with Tarot?). I've removed my original statement because how I read most Oracle decks is quite different to how I read Tarot. With Tarot I access many layers of meaning that I am constantly scanning as the client is responding to the cards and to my questions about them. I'm looking for the pattern underlying their situation, which the Tarot correspondences can reveal. I don't normally read Oracle Decks for others (Lenormand excepted), but use them for myself. Some I go to because the accompanying book's text is a wisdom oracle in its own right. Sometimes it is like a dialog with that voice - either with the text or with the figures on the cards. With some decks I enter the landscape of the cards. Sometimes the figures speak to me. Other decks are purely symbolic - I read messages in the symbols.
For instance, Dolphin Divination Cards (one of my favorites) simply have a word or short phrase on them. Drawing several cards and playing with how the words combine often yields a "click" that generates an answer or salient description. Additionally, the book that goes with them is, to me, filled with wisdom and insight that I can go to as an oracle text and from which I always get a relevant and helpful message to ponder. I tend to like messages rather than definitive 'answers.'