We all have our own methods and what works for one may not for another. Took the liberty of doing a "search forums" for you. You could probably tweak the search and come up with even more threads, but this should get you started.
http://www.chess.com/forum/search?keyword=How+to+learn+openings
Alright so I've been playing the King's Gambit for quite a while now as white, whenever I get the chance to. I'm looking to try to make some sort of formal study of the opening now, actually trying to go past the first three or so moves.
I'm wondering if there's any methods/suggestions on how to efficiently study this opening.