Here's what I would recommend, based on the Yanfly comics and other suggestions that were given to you.
If you have a big idea, get the bones down first. Chances are you don't need to rewrite RMMV to bring a lot of those ideas to life, and, as you familiarize yourself with the program, eventing and even scripting will start to come more easily. Start with a basic premise, and if you don't have the graphics pack, tile sets, animations, scripts, etc. for some elements of your game, first work with what you have and design what you can using what you know.
Then, after you've created something, play test it and go back and make notes on what you want to add. Then, slowly add all of those bells and whistles you were thinking about. This will help you familiarize yourself with coding and game creation overall, instead of relying on complex scripts that you cut and paste and don't really understand.
I'm also going to just name some things that kill game play:
Sending the player on aimless quests
Making puzzles that are almost impossible to solve (if you want to make a puzzle for the player to solve, start out with something easy and then gradually progress the difficulty as the player goes through dungeons)
Not scaling difficulty and making enemies either too easy / too hard
Causing the player to have to "grind" to gain experience or making it where the player can't gain enough experience.
Making levels too big
Making maps too big (if you have to use multiple maps, do so, but don't create a huge map that takes several minutes to load)
Having spelling and grammar mistakes with NPC dialogue and thereby breaking immersion. For example, if the NPC is supposed to be from a well-to-do family, make his dialogue fit.
Not being familiar with the basics of RPG Maker and believing everything needs a script. In reality, most things can be done with events and do not require modifying existing scripts.
(Of course, I'm one to talk. I started out making games using special scripts, and they made somewhat complex game mechanics part of the standard code. Without the scripts, my games don't look nearly as impressive, but at least I am learning something about coding in the process.)