What was your biggest rookie mistake when you first started Master Duel?

So for context I opened the Beloved Dolls pack a couple days into Master Duel and thought that since I pulled "Princess Colonge" I could summon her with two Madolche monsters because they came from the same pack and look similar. It was about then when I started reading the cards in my deck.

So for context I opened the Beloved Dolls pack a couple days into Master Duel and thought that since I pulled "Princess Colonge" I could summon her with two Madolche monsters because they came from the same pack and look similar. It was about then when I started reading the cards in my deck.