Ducks of the first order

 There are two sitting ducks that are around from the get go:

• The center
• The King

While hunting down these ducks, sitting ducks from the second order might well land on your position:

• Outpost square
• Weak pawn
• Invasion square
• Promotion square

Let's focus on the center and the king

From the opening on we focus on the center (d5, e5 for white and e4, d4 for black). We pile up our pieces behind the pawns. We are loading the spring, as it were.

During development, we focus on the tempo battle

• piece movement must have a purpose. Usually that means adding to the domination of the center.
• piece movement with gain of tempo is preferred
• piece movement which adds a pin is preferred
• a development square where the piece cannot be kicked away is preferred
• a development square where the piece doesn't enter a pin is preferred

Pieces that have no effect on the center are pseudo developed.

Spring into action

Once the center is dominated and all pieces are developed, the central pawns start to roll. This has the following effects:

• The pieces that used to protect the center pawns come to life. The now empty squares behind the pawns can be used by knights in order to approach outposts in the vicinity of the opponent's king. The moving pawns do open new lines of attack. Diagonals for your bishop, for instance.
• The moving pawns can kick away pieces of the opponent. Thus gaining tempi while confusing the coordination of the enemy pieces
• Prying a wedge into the enemy camp. Thus creating a distance from potential defenders to the enemy king

Balance

When the focus shifts from the center to the enemy king, we must be aware of the balance between the potential amount of attackers and the potential amount of defenders. How many tempi are needed to add extra attackers, how many tempi are needed to add extra defenders? Which defenders are simply cut off from the king? This tells you how many pieces you can sac.

Sacrifices

These are common ways to change the balance by force:

• Passive piece sacrifices that deflect your opponents defenders to places where they are virtually inactive
• Saccing a piece in order to get rid of an active defender (rook for a knight, for instance)
• Pawn sac in order to open lines of attack for your pieces