Consider how modular you want what you are making to be. There is a trade off. The more modular, the more abstract and difficult the design becomes, but the easier it is for you to implement content. Alternatively, if you are extremely specific, spaghetti code will make your project fall under its own weight.
You could also consider making a mod system. Generally, if you make something easier to anyone to add to, you make it easier for your self.
Also, feel free to ask me more specific coding questions.