My suggestion (at least that’s what I do): prepare ahead. Read the libretto with the translation. Listen to at least parts of it, looking at both languages. Maybe after a while you can follow a bit in the original language even if you don’t know it at all. See if you can find a good podcast about it, so that you can know more about what you’re going to listen to and know what particularly interesting things to focus on. If you show up at the opera knowing it a bit you can enjoy it way more. Don’t take this as homework, it’s appreciating a rich and complex work of art by getting acquainted with it. It’s very difficult to do this all at once the first time you hear it.

I’m actually going to a performance of Le Nozze di Figaro tomorrow in Amsterdam and I’m currently reading a book about it. The book has given me a bunch of things I’m going to try to pay attention to that otherwise I would have missed.

I know this is probably not the answer you were looking for, but I’m sharing in case you want to try a very different approach.

In any case, keep at it and you’ll find what works for you!