With his crystal clear, logical style of play, GM Gligoric has created many instructive games that allow you to understand the ideas of a particular opening pretty quickly. That's why the excellent book "I Play Against The Pieces" by Svetozar Gligoric is not just a collection of great games but also an excellent opening manual. I have described my favorite method for opening preparation in many of my articles.
One of them explains it in detail: http://www.chess.com/article/view/how-to-learn-an-opening-in-one-hour
Say you answer 1.e4 with 1...e5, in this case you have to be prepared for the King's Gambit. This opening is not particularly popular these days, but can be deadly to an unprepared chess player. Now you have a choice: spend a lot of time studying opening books, or just replay and understand the next two games by Svetozar Gligoric:
Sometimes just one Gligoric game can help you solve a complex opening problem. For example, if you play 1.d4, then you need a weapon against the Cambridge Springs variation of the Queen's Gambit. Many generations of chess players have been solving the problem of finding an opening advantage, but still it is not that easy to do. For instance, this opening was a reliable defense for Alekhine in his World Championship match against Capablanca where the great Cuban couldn't convincingly break Black's defense.
Here is a simple solution from Gligoric: just prevent it and force your opponent to play in an unfamiliar situation!
to be continued...