About the Cards
As there are several, several versions out there, find one that resonates with you, use it, and don't worry about whether somebody else is using a different system or not. The card definitions I have listed here will be separated into three categories: cartomancy, piquet cartomancy, and tarot.
The order of the suits...
♥ ♣ ♦ ♠ — Common
♣ ♦ ♥ ♠ — 19th Century
♦ ♥ ♣ ♠ — 20th Century
♣ ♥ ♦ ♠ — Tarot (Wands, Cups, Pentacles, Swords)
♠ ♣ ♦ ♥ — Modern Games
♠ ♥ ♣ ♦ — Modern Games
While three of the suits are placed in any position, the final position is often reserved for Spades due to its ominous and foreboding meanings.
Mr. Willis tells me that Etteilla is considered an authority on card definitions, and that Robert Chambers also holds a lot of clout in the cartomancy world and many definitions can be found derived from him. While English-speaking countries tend to favor Arthur Edward Waite, the rest of the world still prefers Etteilla. According to my research, most would not have known about divination with Tarot cards without his initial influence. Considering Etteilla's age, I would have to agree with Mr. Willis.
If you would like to read the origins of each of these definitions and trivia on my site for yourself, you may do so by visiting the Sources & Links page.
Cards and Decks
Your plain playing card deck is probably one of the most common decks used due to its availability and affordability. It has 52 cards and often a joker or two. Depending on the method of card reading used, the inquirer is represented either by an appropriate suit card or by the joker. Sometimes the jokers are used to represent the tarot cards 0 The Fool and 21 The World.
There is a special kind of deck called a "piquet" deck. It consists of 32 cards from a playing card deck; the 7s, 8s, 9s, 10s, Jacks, Queens, Kings, and Aces of each suit. Cards 2 through 6 of the deck are removed. Marie-Anne Adélaïde le Normand, known best for her namesake the Lenormand deck, was a famous card reader who used a 32-card deck and is said to have read for Napoleon Bonaparte himself, along with other famous people of France. Mlle. le Normand was a follower of Jean-Baptiste Alliette, who was in turn better known as Etteilla. Etteilla's method of divination with a piquet deck is often called Petit Etteilla.
Tarot decks consist of 78 cards. There are 54 minor arcana cards, which are the same cards of a standard playing card deck plus a Page for each suit, and there are 22 major arcana cards numbered 0 to 21. Some tarot decks will have a unique set of definitions that are provided with them.
Oracle cards vary in number between decks and tend to have their own reading systems that come with each deck. As they are so varied, I will not be listing any of their definitions here.