To the excellent advice above, I would also add this: read the history, myths, and legends that inspired Tolkien.
Tolkien wasnāt just a linguist, he was a historical linguist. He knew language arises out of a place and time and culture. You canāt translate Old English and Middle English into Modern English without knowing that. Read Tolkienās translations of Beowulf and Sir Gawain and the Green Knight and youāll see what I mean.
Hell, so many big names (Tolkien, GRRM, Herbert) have entire plot lines, scenes, and lines lifted wholesale from the historical material that inspired them. The canon they draw on is part of what gives them their timeless quality and depth. The lesser-known inspirations they draw from also are arguably responsible for so much of what made their work fresh and exciting. Itās not that TĆŗrin Turambar is Kullervo, itās not that Game of Thrones is the Wars of the Roses, itās not that Dune is The Sabres of Paradise/the Murid War. Rather, itās that thereās an artistry to being inspired.
And frankly I think stuff begins to get stale when inspiration comes second- or third-hand.
Iāll never forget how fresh Poul Andersonās The Broken Sword felt to me, because he and Tolkien were dipping from the exact same wells. You can tell which bits of sagas and myth theyāre both drawing from, and it feels exciting because theyāre both doing such extremely different things with it. Meanwhile, you can tell when someone is getting their dwarves exclusively downstream of Tolkien. They start to feel a little inbred.
I also think we need to stop doing the photocopies of Tolkienās photocopies of The Kalevala and The Nibelungenlied. We do need to read those to keep Western fantasy, as a literary tradition with its own inspirational canon, from limiting itself. But we also need the same enthusiasm people bring to reading Norse sagas to be brought to The Shahnameh, The Kebra Nagast, The Romance of the Three Kingdoms, The Mahabharata, or The Secret History of the Mongols.
I think an accurate knowledge of Western history alone would root out a hell of a lot of the racism and gender bullshit in fantasy. Not even gonna touch on how much better fantasy religion would beāthatās its own post. All this is still me dreaming within Eurocentric constraints. I canāt even imagine how incredible things would be if the horizons of inspiration were truly blown wide open.