Django：将项目分成应用程序的最佳实践

I'm really struggling with this whole app-idea. I read a lot of tutorials and style guides and I know I should try to create specialized apps, that do exactly one thing. This all makes sense when looking at some simple tutorial project but as soon as it gets to a complex real life project, I find myself unable to determine how I should draw the lines between different apps.I'm really struggling with this whole app-idea.