What maker are you using?
My process for game making is to first take a paper and draw and write everything that comes to mind. I don't care if things are completely incompatible or impossible at this point. It could be plot, character, but my main focus is gameplay first.
Since it's your first game, I wouldn't expect you to have a fully custom game with hours and hours of gameplay and a brilliant story. I'd keep it simple, in fact. The main thing is [x] You take a look at every event command/help file and have a basic understanding of what it does, [x] get a sense of how long it would take to make x (where x is either a map, a cutscene, an evented scene such as a puzzle or minigame, and the whole game itself), [x] finish a game, no matter how short it may be. I'd keep the default graphics for the first project, but you can play around with them a bit so you know how to do it for a next project.
Basically, I'd use it as a practice game. If you have a brilliant game in mind, then don't make that game. Make something that has the ideas that you want the brilliant game to have. For example, if you want an action RPG for your game, you could try an experimental game with a simple action RPG script, or some events (it would be good to learn the events anyway) for basic enemy moving around, switches and things like that. Otherwise, what tends to happen is that the first part in your game ends up far worse than the later part of the game and you have to redo that...
In a game itself, I like to plan the gameplay first. I can always adapt the story to fit the gameplay later. The main thing is that I hope I can get a fun system first.
Gameplay balance is not an easy thing to do. You may want to familiarize yourself with the battle formulas, but mainly those things largely come down to play test and adjust, play test and adjust, play test and adjust. You may end up playing your game a whole lot just to make sure everything works and doesn't bug (I tend to test every little thing I do just to make sure it works as expected).