I'm doing a rpg as well. I started with the huge dungeons tutorial on the dbpro site, and am putting together the 3D engine that i will use.
Once I have figured out how to do everything I want to do, I'll probably re-code to make it cleaner, then start developing a plot, characters, so forth.
The reason I'm doing it this way is I find it easier to get the technical stuff out of the way, have a clear idea what I can acomplish from a coding side. Once I have that, the creative juice starts rolling, and if it takes me somewhere I need more code, I can always write more later!
Anyway, that's my two bits worth. I do recomend starting with that Huge Dungeons tutorial though, lots of good stuff! Good luck Idiot, you'll find the journey difficult, but rewarding I think.
Think Gad fro Spill Chock!