If you know anything about or are interested in learning how to program, learning Ruby would be highly beneficial.
I'm sorry to say this, but unless you're already experienced with game making, your first project (probably) won't be anything good even if you do your best. Personally, I would advise you to start practicing mapping and perhaps some random cutscenes to get familiarized with the different event commands - checking out some tutorials would do you good since you're new.
If you're anything of a dreamer, you'll often envision random bits of dialog and etc.. When you get the chance, put those into RMXP format and once you're acquainted with the program, you can start thinking of a game. Most of the times, the game idea will just flow onto your mind; pressing yourself for ideas will, most likely, result in a bad game. Once you have this general idea (the game concept, plot, perhaps even detailed characters), start making or otherwise, if you don't have any RMXP-related skill (scripter, spriter, musician etc.), collecting the resources you need and putting them into place.
If you're anything like me, you'll need a lot of willpower to stick with one project even though new/better ideas are constantly showing up on your mind.