MCO has summary about opening or defense and going through the lines you be familiar with pieces placement and pawn structure and one or two model games and a player will have some understanding. Another way is repertoire book on the opening or defense with complete games and with annotation. I love to see low rated amateur go through fifty GM games one particular opening without any annotation, it won't never happen, they can't even go through an opening repertoire book with explanation and annotation; because its left on the shelves collecting dusts. Is this the joke for today.lol Its not April Fools 4-1-2018.
I'm going to guess that the way you learned your first openings was either because somebody showed you some interesting openings or you saw some complete games that were annotated in a book. Those games could have come from Chernev, or as it was in my case, games from Spassky-Fischer 1972 and Alekhine's Greatest Games book.
I sincerely doubt very many players who first came to chess by looking at opening books ever became expert strength players. I can't imagine a player falling in love with the game enough to study it in depth by opening MCO.
Petrosian's recommendation of studying complete games, and others' recommendations of finding well-annotated games in a given opening are excellent and time-tested methods. Resorting to reference material on a specific opening should be one of the last steps in choosing a repertoire, not a first step. The reference material will help the player to solve specific move-order issues, but they aren't a substitute for experience.
There's an old criticism of COTAP (Chess Openings: Theory and Practice by Horowitz) and MCO that is still pertinent:
Those books will give you just enough information to get into trouble, but not enough to get out of it.
Before I give my own response, let me point out that I disagree with the question in the thread title. Until your first name is "Grandmaster", there's no such thing as "best". It's all a matter of what you want to play.
I don't like the 4. d3 stuff that's popular with GM's these days. If I wanted slow maneuvering that way, I'd play the Ruy Lopez. I go for the Italian to play aggressively, so I play the c3 and d4 line. But I go with Sveshnikov's e5 sideline instead of the usual Moller Attack, just because it's less well known.
I have Pinski's book on the Giuoco Piano and Evans Gambit, where he says this isn't good enough. He's probably right, but that's GM level theory. Below master level, it's certainly playable, and most opponents don't know it, so I always get a good game. When I used to play the Moller, I had a couple of games that stayed in book 10-12 moves, because people memorize that as the main line, but I didn't know how to proceed from there. In this, I know the most common responses after move 6, and most of my opponents are improvising, so that gives me an advantage from knowing the opening better than they do.
I've tried the Evans Gambit (4. b4) here and there over the years, just for variety. But opponents are more likely to know how to handle it, so it requires more study than I'm willing to commit.
the max lange attack that i had said:)
Sveshnikov's line is quite different from the Max Lange (pawn on c3 instead of 0-0).
More than that, the Sveshnikov variation can be more or less be applied by force, while the Max Lange will not happen if Black does not comply.