Best Way To Learn Openings ?
Basic principles are always a good place to begin and where many amateurs go wrong.
Books like Ward's "Improve Your Opening Play" and Fine's "Ideas Behind the Openings" are great for getting a quick survey of what all the openings look like. And you'll get a better feel for how and why to apply basic principles.
At this point, I mostly study recent annotated games in my chosen lines to get a good idea how masters handle the positions. I also analyze my own games to compare how I handled the resulting opening, middlegame, and ending.
Is it sensible to study one opening and keep at it until you master it then move on to the next, or does it sink in better to choose a different one to study each day until you get to know them all ?