Arabic. I think the first thing is to study Arabic (assuming you've already learned the essential basics like how to do the daily prayers and assuming you're already studying the Quran).
I would recommend you go to this website https://www.sifatusafwa.com/en/ (bookstore of Arabic Islamic books), that you browse, find some books on topics that interest you and try to read these books. If you are reading quality Arabic Islamic books.... I don't think you'll be interested in books by non-Muslim intellectuals. The Arabic Islamic books are way superior. And on that website, they have books on different topics. Aqeedah, tafsir, if people want books that are tailored for women, there are books that are geared towards women... once a person is immersed in the Islamic knowledge, like I said, I don't think they'll really be interested in wasting their time with the non-Muslim intellectuals.
