Common beginner mistakes include bringing the queen out too early, ignoring development, and leaving the king in the centre without castling. New players often focus on one piece instead of coordinating several, hang pieces by leaving them undefended, and chase pointless checks that only help the opponent develop. Other frequent errors are moving too many pawns, forgetting to watch the opponent's threats, and trading good pieces for bad ones. The fix is simple: after every opponent move, ask what it threatens, keep your pieces defended, and follow the opening principles of centre, development, and king safety.