I read this after a HUGE beat down I suffered at the hands of a 12 year old girl while playing in my first tournament after not competing for 7 years. It was the U.S. Junior Open, I was 21 and this was my last chance to play in a Junior Championship before turning 22. I was super excited!
Man, I was completely unprepared for a tournament outside of a scholastic setting. I lost all 3 of my matches with black, playing the Kings Indian defense... my favorite defense as a kid to [1. d4] with my preference being the Samisch Variation. Perhaps my overconfidence hurt me when all three of these matches went down a familiar path.
This was a very good overview of the main variations, and was perfect to help me dry up the tears after watching the 12 year old squirm in her chair after realizing she was going to win.