There is no one specific recipe for a good RPG (assuming that we talk about a game made with RPG Maker MV), keep that in mind that games made with MV (or any RPG maker) are very recognizable due the specific tilesets style and turn order battle system, but if I were you I would do following:
- Think your project to whom you're making a game and create a small community that would support you with your project development.
- Read some books, or listen few interesting stories and develop your own story (without haste)
- If you're no artist, then fine, keep with default tilesets, after all there are not so bad as people think
- Play some other games and see how they do battles, there are dozens plugins that alters default battles in MV
- Create charismatic/memoriable heroes, you should find inspiration in heroes from your childhood, a heroes you really liked/admired.
- Sounds and music also is important, you should check Creative Common libraries to find a music matching climate of your project.
Now this is pretty generic, but if you totally focus on one of these elements then you're half way of success, the rest is up to you, managing free time to spend on game and other stuff.
Finally, the most difficult part - marketing, because even god damn good games without marketing (a good one) marketing won't be able to get through all other s**t you can find on steam. In other words you need to know how to tell people that your game is better than others.
I think that's all for now.