Original sources are paramount to any real sense of understanding. In my opinion the best approach is reading primary and secondary material in tandem. Understanding ideas is important obviously. But there’s also something to be said about the experience of navigating a difficult text and beginning to grok it, and the process itself is rewarding and worthwhile.

That said if the person asking this question has no interest in being an academic, your advice is horrible. Imagine reading about Plato but never reading a dialogue, never getting a sense of being in a room with Socrates. Imagine reading about the death of God but not a single sentence of Nietzsche’s maddeningly beautiful prose. You need to engage with real philosophy.