Learn to use a chess program, eg ChessBase, in order to improve speed and efficiency (when studying the opening), and to make study more fun. Andreas Tzermiadianos, How To Beat The French Defence
At master level (approximately 2360 elo) and above, a pawn deficit is generally decisive. From there down to 1800 elo a pawn deficit on its own need not be disastrous, unless the inferior side cannot avoid a simple losing endgame. Below that level, a two-pawn deficit (or a piece for a pawn or two) can often be overcome. David LeMoir, How To Be Lucky In Chess
If your opponent ends up with an isolated pawn, make sure you control the square directly in front of it. Aside from stopping the pawn in its tracks, the square will turn our to be an excellent home (support point) for one of your pieces. Jeremy Silman, The Reassess Your Chess Workbook
The command of an open file by a rook, or by both rooks, represents a great advantage, particularly if the file is the only one open, and the opponent cannot reply by occupying it with a rook. Siegbert Tarrasch, The Game Of Chess
In the opening and in the middlegame, the loss of a rook for a minor piece and one pawn is usually less serious than the loss of a pawn. Cecil Purdy, On The Endgame