Three Cs of chess strategy.
1) Controlling the center: Control the four central squares to give your pieces maximum mobility and influence over the entire board.
2) Castling: This key to king safety moves the king away from the center (where the action is) and brings a rook toward the center.
3) Connecting rooks: Move your minor pieces (knights and bishops) and the queen to establish a connection between your rooks on the back rank.
These are fundamental principles for beginners that are also applicable in the vast majority of intermediate and advanced games. (drawn from the House of Staunton website)