The Thirty Rules
TEN OPENING RULES
1.OPEN with a CENTER PAWN.
2.DEVELOP with threats.
3.KNIGHTS before BISHOPS.
4.DON'T move the same piece twice.
5.Make as FEW PAWN MOVES as possible in the opening.
6.DON'T bring out your QUEEN too early.
7.CASTLE as soon as possible, preferably on the KING SIDE.
8.ALWAYS PLAY TO GAIN CONTROL OF THE CENTER.
9.Try to maintain at least ONE PAWN in the center.
10.DON'T SACRIFICE without a clear and adequate reason.
For a sacrificed pawn you must:
a) GAIN THREE TEMPI,
b) DEFLECT the enemy QUEEN,
c) PREVENT CASTLING,
d) BUILD UP a strong attack.
TEN MIDDLEGAME RULES
1.Have all your moves fit into definite plans.
Rules of Planing:
a) A plan MUST be suggested by SOME FEATURE IN THE POSITION.
b) A plan MUST be based on SOUND STRATEGIC PRINCIPLES.
c) A plan MUST be FLEXIBLE,
d) CONCRETE, and
Evaluating a Position:
2) PAWN STRUCTURE,
3) PIECE MOBILITY,
4) KING SAFETY,
5) ENEMY THREATS
2.When you are material AHEAD, EXCHANGE as many pieces as possible, especially QUEENS.
3.AVOID serious pawn WEAKNESSES.
4.In CRAMPED POSITIONS free yourself by EXCHANGING.
5.DON'T bring your KING out with your OPPONENT'S QUEEN on the board.
6.All COMBINATIONS are based on DOUBLE ATTACK.
7.If your opponent has ONE or MORE pieces EXPOSED, look for a COMBINATION.
8.IN SUPERIOR POSITIONS, to ATTACK the ENEMY KING, you must OPEN a file (or less often a diagonal) for your HEAVY PIECES (QUEEN and ROOKS).
9.IN EVEN POSITIONS, CENTRALIZE the action of ALL your PIECES.
10.IN INFERIOR POSITIONS, the best DEFENSE is COUNTER-ATTACK, if possible.
TEN ENDGAMES RULES
1.To win WITHOUT PAWNS, you must be at least a ROOK or TWO MINOR PIECES ahead (two knight excepted).
2.The KING must be ACTIVE in the ENDING.
3.PASSED PAWNS must be PUSHED (PPMBP).
4.The EASIEST endings to win are PURE PAWN endings.
5.If you are ONLY ONE PAWN ahead, EXCHANGE PIECES, not pawns.
6.DON'T place your PAWNS on the SAME COLOR SQUARES as your BISHOP.
7.BISHOPS are BETTER than KNIGHTS in all but BLOCKED pawn positions.
8.It is usually worth GIVING UP A PAWN to get a ROOK ON THE SEVENTH RANK.
9.ROOKS belong BEHIND PASSED PAWNS (RBBPP).
10.BLOCKADE PASSED PAWNS with the KING.
(source: chess dryad.com)