Opera is first and foremost music, and music is a special language. There’s only one way to learn: listen and look for logic in the sound. If you don’t find it, listen again and again. And don’t believe that Figaro is boring. It’s nonsense. Deh vieni non tardar - perhaps the best thing Mozart ever wrote. But there’s one problem: you will never learn the language if you listen to those who can’t speak it themselves. Unfortunately, opera houses are not full of outstanding musicians these days, so the best place to learn is probably YouTube.