Start with a Respectful Greeting
The official Yugioh rule book asks players to greet each other before beginning to battle. Opponents should give each other a friendly, firm handshake. Each player must shuffle his or her deck thoroughly. Players may also decide if they want to exchange decks with their opponent, and have them shuffle the deck as well. Once they have been shuffled, decks should be returned to their respective players. Each player must then play his or her deck face-down on the appropriate deck space of the game mat.
A Coin Toss Decides
The winner of a match is the first player to win two out of three duels. Players should flip a coin in order to decide who will begin the first duel. The player who wins the coin toss can decide to go first, or can choose to go second. After the first duel has been played, the loser of each subsequent duel decides whether to go first or second. If a battle ends in a tie, players should conduct another coin toss in order to decide who will go first.
Be Loud and Clear
The Yugioh rulebook stresses that each player must always declare each move in a loud and clear voice before conducting any move.
Fusion Monster Cards
Fusion Monster cards are special cards that have an etiquette all their own. A deck of Fusion Monster cards is created in the course of a battle by combining two or more monsters. A player can “fuse” two cards together with the use of the “Polymerization” Spell card, thereby created a new, more powerful monster out of the two discarded Monster cards. Each Fusion Monster card details what two normal Monster cards must be used to create that specific Fusion Monster.
Also, unlike most cards, Fusion Monster cards are not included in the 40 card minimum of the Dueling Deck. Players who use Fusion Monster cards must always place the cards face-down on the appropriate space (the Fusion Deck Zone) on the Yugioh game mat.
Side Deck Cards
Players in order to modify and improve their primary Dueling Deck use side Deck cards. The Side Deck must contain exactly 15 cards. Cards from the Side Deck can be exchanged for cards in the Dueling Deck, as long as the number of cards in the Dueling Deck remains the same. Proper Yugioh etiquette requires that you count out the cards in your Side Deck so that your opponent(s) can see that you are only playing with 15 cards. Side Deck cards must always be counted face-down so as not to reveal their identity. Every time players exchange cards from their primary Dueling Deck with those in their Side Deck, he or she must re-count the cards in their Side Deck to ensure they are only playing with 15.
Graveyard Cards
According to the Yugioh rulebook, players must always be honest about the content of their Graveyard. The Graveyard consists of any discarded cards. These cards must always be kept face-up. They are public knowledge, and must never be kept hidden or obscured from other players.