ITT zulhilmi tells us obvious things we already know in a dramatic manner.
Don't memorize the openings!!!
Only memorizing the moves is wrong also because you won't be able to punish the players who don't follow the book. I mean, if you learn the principles of opening you can play quite correctly in every case, not only in the particular book line.

Like me, I always play e4 as white, and familiarizing every variations of that move helps a lot. After my opponent, I can make a move that is a specific reply. Chess opening principles are still the best to study.
If you study openings, you study openings. If you study endgames, you study chess.
As far as I'm concerned, most players will keep on focusing in which is the best opening by giving them values, etc. But what they don't understand is: PEOPLE CAN MEMORIZE 20 STEPS AND STILL LOSE! So, what's the point of arguing which is the best opening? I would suggest that people start to understand the principles behind the opening and apply them wisely. If we simply memorize the opening, we will be shocked if our opponent twist a little bit and we can lose the game. Here is some general ideas about chess opening:
1) What is the goal?
2) What is the weak square in the position? Can we cover it up?
3) The attack is focusing in which area of the board? left, centre or right?
4) What is the strong point of the opening?
5) Can we turn it into a great variation where our attacks are organised?
6) What if we get attacked early? Can we defend it with our opening?
7) What's the common goal of our opening with their defence?
8) Is the opening allows a surprising sacrifice that will lead to much better position?
9) What advantage will our opening give to the opponent? Can they exploit them effectively?
10) What about our king's safety??
Well, that's all I can discuss about chess openings. Feel free to comment becoz I'm not perfect :)