I often find myself during development slipping back into bad practices and having to beat good ones into my head.
A good habit for game development in Unity is making prefabs. Prefabs ensure that you are following the principle of DRY.
In the case of game objects, this includes everything from Characters, Enemies, Platforms, Weapons, Scripts and anything you will have to use more than once (which in Game Development is a lot of things).
Prefabs are useful, and I am trying to force myself into writing reusable code.
Here is a short tutorial on YouTube showing How to create Prefabs in Unity.
I am also keeping a list of the tutorials I am using throughout my project on YouTube.