Eeeeep, another Elric fan, yay!
Speaking of metal songs about Elric, @nathanKmcwilliams, Blind Guardian's Tanelorn is also inspired by the Elric saga 
Now, as far as the topic goes... there are already a lot of amazing sugestions here! I definitely recommend checking out Sanderson's lectures, but yep, definitely keep in mind that "fantasy" is a very broad genre, so a lot depends on what you're trying to do. A high fantasy setting (basically what you have in Lotr: fictional world with fictional creatures) is gonna require a LOT more planning, since you basically have to create an entire universe from scratch... but that doesn't mean that a low fantasy (aka, a fantasy set in our own universe with only a bunch of fantasy elements) doesn't require any sort of work either: since you're bringing fantasy elements to the mix, you still need to think how to make them fit the universe of your choice! I definitely recommend reading more fantasy books/watching movies/series/cartoons/reading comics of the genre you're interested in... and also why not, search on Youtube for videos that analyze your favorite fantasy works to help you figure out how they work exactly. This guy seems to do just that
(also, another huge favorite of mine would be this dude: yes, his videos are sarcastic and things he says should be taken with a grain of salt, but they also offer some interesting food for thought when it comes to worldbuilding
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