Rooks are the Key

Any opening that caters to the rooks will automatically be a good one for the other pieces.

We should test any opening chiefly by the prospects it offers to ambitious young rooks.

 How is a rook to blossom? In one way only: through an exchange of pawns. Such an exchange need not be hurried. It is sufficient if the possibility of exchange is there on the board, ready to be utilized at any time.

Four Tests on Where a Piece Should Go in the Opening

The ideal square for a piece in the opening will stand the following tests:

1. The piece can go there in one move.
2. The piece will be effectively posted there.
3. The piece will not suffer from exposure.
4. The piece will not unduly obstruct any of its own forces.

Rarely can you find a square that passes all these tests, but try to get the square that passes test 3 and as many of the others as possible.

- CJS Purdy

General Principles: Openings Pt. I

The main aim of the opening is to get all your pieces into working order - i.e. developed. The moves of the minor pieces and the Queen have a double purpose:

1. to get those pieces into play themselves and
2. to clear the back line for the rooks.

Development is complete when the rooks are connected on the back rank and at least one of them is on an effective file, both if there two effective files. (pg. 44)

The second aim of the opening is to get a good share of the center squares.

Where you don't play e4 (...e5) early, never block your c-pawn. (pg. 45)

Don't finachetto a bishop if an avenue is already opened to it. (pg. 45)

Do not let a bishop be shut in by a one-step move of the e-pawn or d-pawn. (pg. 46)

To see how you stand in development see how many moves each side needs before their rooks will be connected, with one rook on an open or half-open file. Add on half a move (or "tempo") for the player whose move it is, and take the diference. If one player is 2 1/2 tempos ahead and has a good share of the center as his opponent, then that player usually has a winning advantage (advantage of a pawn plus). (pg. 46)
An exchange loses a move(a "tempo") if the opponent recaptures with a developing move. (pg. 47)

To avoid getting behind in development refrain from playing any non-developing move, unless you can compel the enemy to make a non-developing move to counterbalance yours.  (pg. 46)

Consider taking a center pawn if the pawn is threatening to take your pawn or to advance and hit a piece. (pg. 48)