Try to avoid making passive moves just to defend weak pawns. Sometimes they cannot be avoided, but often the pawn can be sacrificed for activity. Richard Palliser, Starting Out: Sicilian Najdorf
The presence of a bishop on the long diagonal [a1-h8] and a knight on f5 is a clear warning that something unpleasant is about to happen on g7. David LeMoir, Essential Chess Sacrifices
Tactics don't always work. If your opponent starts some tactics, it is important not to accept his idea at face value, but to look at it sceptically to see if it might contain a flaw. John Nunn, Learn Chess Tactics
A sacrifice of material in order to achieve a superior pawn-structure is often a typical method for the side wishing to obtain a static advantage. Valeri Beim, Lessons In Chess Strategy
If one wants to decline the King's Gambit, 2...Bc5 has to be the most logical way, taking over the critical g1-a7 diagonal and preventing White from castling. John Watson, Mastering The Chess Openings - Volume 1
The club player often describes himself as having an 'attacking style' or a 'positional style'. When the sharp tactician falters in a quiet positional struggle, he blames it on 'not being my type of position'. If you think in this manner, you don't have a style, you have weaknesses. James Rizzitano, Understanding Your Chess