Good ways to learn openings

Am not new to chess but I am struggling to get openings downpat. Any tips from experienced players?

Play first, review your games later.  I did this recently when switching to the Gruenfeld as Black.  I had some rough ideas about the opening, but just started playing it, then looking things up later.  Now in some lines I'm booked up 15 moves deep

In a 2006 GM John Nunn book, in connection with opening study, it is stated that, if a "book contains illustrative games, it is worth playing these over first", and the reader was also advised, "To begin with, only study the main lines - that will cope with 90% of your games, and you can easily fill in the unusual lines later."

"... I feel that the main reasons to buy an opening book are to give a good overview of the opening, and to explain general plans and ideas. ..." - GM John Nunn (2006)

In one of his books about an opening, GM Nigel Davies wrote (2005), "The way I suggest you study this book is to play through the main games once, relatively quickly, and then start playing the variation in actual games. Playing an opening in real games is of vital importance - without this kind of live practice it is impossible to get a 'feel' for the kind of game it leads to. There is time enough later for involvement with the details, after playing your games it is good to look up the line."

Study  the opening from both sides.  Play games from both sides.  Study  master games. 

The goal is to build in your brain a visualization pattern memory bank of the opening, middlegame and endgame.  This way  you  may have some of the moves memorized, but when your opponent makes a suboptimal move your visualization pattern memory bank will come to the rescue on how to respond.  In other words, you have built a familiarity with  the characteristic positions in  the opening and how to handle them with either color.

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