Developing a piece means moving it from its starting square to a more active one. In the opening, your Knights and Bishops are your most important tools. After developing your Knights and Bishops and castle your king, you need to always develop your Queen and Rooks.
The Best Path: Generally, after castling you should move your Queen somewhere safe and active to connect your rooks. After that you should move your rooks to open files and semi-opened files to make the rooks more acitve. This helps us complete our development and get ready for the attack.
Beyond simply moving pieces out, high-level development prioritizes "King Safety" and "Rook Connection." By developing the minor pieces and the Queen, you clear the path for castling, which tucks the King away into a protected corner behind a wall of pawns. Once castled, the Rooks are "connected" along the back rank, allowing them to support each other and contest open files. This coordinated setup is the hallmark of a successful opening; it signifies that the army is fully mobilized and ready to execute complex tactical maneuvers or long-term strategic plans.