First problem is making "prequels". Casual viewers are not as enamored of the "prequel" idea as fans, but fans also have their own vision in mind of "what came before" and if your prequel radically differs from that you're already off on the wrong foot. This was Amazon's biggest mistake IMO - they didn't have the rights to all of the prequel material that Tolkien had written, so they used what they were allowed to use and wrote new stuff around it. No matter how good it is the fans are going to hate it and the casual folks are just not going to care because it's a prequel.
Make it a sequel, set it a century after the original and tell a new story. Divorce yourself from the idea that your target audience is fans who are deep into the material and instead target mass appeal. You might miss but at least the work has a chance of being judged on its own merits rather than being compared to the prequel material that each individual fan carries in their own heads and that you're never going to be able to live up to.
(This is my general attitude towards prequels in general - just stop. The original story probably started at the point it did for a reason. Probably because "what came before" is not interesting enough to tell as its own story. It's generally fine existing as backstory that doesn't need its own movie and is going to be more interesting as vague ideas of what came before instead of something concrete. But it's even worse for LotR because it has the existing twist that Tolkien had already written prequel material that they weren't able to use. )
Lucas in 1977 started Star Wars from Episode 4 instead of Episode 1 for a reason. In 1999 we saw why - starting that story in media res with the Empire at full power and the rebels at their lowest point was exciting - it was a tight, coherent story that was easy to jump into and understand as a casual filmgoer. The story about the fall of the Republic was ... less so. Part of that is Lucas's own storytelling abilities not having the chops to write a script centered around the political drama, but mostly it's just that the fall of the Republic is more interesting as backstory that we can all fill in how we want. 
