Openings play

 The next step is to incorporate the opening in the strategy. When there are no weaknesses, your only weapons are tempi and pivotal squares.

• Develop your pieces to meaningful squares
• Don't move the same piece twice
• Develop with tempo whenever you can

What are meaningful squares? A meaningful move of a piece is a move that fights for a pivotal square. A pivotal square is a square on a line of attack. During the opening, these are the center squares. So:

• a piece aims at the pivotal square
• a piece aims at the defender of a pivotal square

When there is a pawn on a pivotal square, that isn't necessarily a problem. As long as the pawn is mobile or is an attacking unit in itself. Look at the following diagram:

White to move

rnbqkb1r/pp3ppp/4pn2/2pp4/3P4/3BPN2/PPP2PPP/RNBQK2R w KQkq c6 0 5 

Blacks last move was c5. Which isn't a bad move, of course. But you need to realize, that it makes the d4 pawn mobile. And a mobile pawn leaves a pivotal square in its wake.

This means that b3 Bb2 isn't necessarily a bad bishop. But even after cxd4 exd4 a bshop isn't necessarily bad.

Black to move

r2q1rk1/pb3ppp/1pnbpn2/3pN3/3P4/PP1B4/1BPN1PPP/R2Q1RK1 b - - 2 11

Bb2 bolsters the e5 outpost. Black can't get rid of  Ne5 without getting a pawn in return OR without weakening e6 (after f6)