If you seize a large hunk of the centre in the first moves of the game, make sure that you can defend the pawns that control that territory. John Watson, Mastering The Chess Openings - Volume 1
The ideal which lies at the root of every operation in a file is the ultimate penetration by way of this file into the enemy's game, that is to say to our own seventh or eighth rank. Aron Nimzowitsch, My System - 21st Century Edition
The general objective every chessplayer should have during the game is to secure a harmonious cooperation between his pieces and pawns. Alexey Sokolsky, The Modern Openings In Theory And Practice
When there is a structural imbalance, opposite-coloured bishops tend to favour the attacker because the defender is often powerless to prevent the infiltration of his position. James Rizzitano, Understanding Your Chess
The conditions for a successful wing attack are either an advantage in the centre or at least a solid, albeit passive central position. Luděk Pachman, Complete Chess Strategy 3: Play On The Wings
Winning chess has a lot to do with playing good moves, but it has more to do with not playing bad ones. If you play 10 excellent moves, 10 average ones and then a lulu, there is every likelihood that your opponent may still win without having played as well as you for 90% of the game. Ian Mullen, Master Chess: A Course In 21 Lessons