Heya!
I believe the best advice for a first project is to start small. Go in with the intention of making something that largely exists to familiarise yourself with the tools first and foremost rather than the dream game you want to make. Because I understand how appealing that may seem at first, but as you've experienced firsthand, burnout and mental blocks can come in swift and fast and be quite demoralising.
But if you make something small and simple, like say, just a test game with a single town, a single dungeon, with limited characters, enemies and such, you'll feel quite a sense of accomplishment when it all comes together and you realise you can indeed see a project to completion.
Will the first project you make be the best thing ever? Probably not! Will it be worth publishing and putting out there? Again, probably not. (Again talking about test projects here!) But the biggest thing you'll get from it is experience. You'll be more familiar with the tools. Know what works and doesn't work. You'll be able to get more daring and expand more in future projects--and perhaps build up to making the large project of your dreams eventually.
Making an RPG, even on a small scale, is a big undertaking between balancing the mechanics, fleshing out the maps, and of course the writing. It's a loooong journey to get even a shorter RPG with a few hours of gameplay. That's why I advise the smallest scale test projects to build up confidence and not get too demoralised in case you stall out on a far larger thing from the get go.
Of course, everyone has different ways of developing that work for them--but I hope it helps at least in a small way if you're feeling lost right now and looking how best to approach things!