Hey, just noticed Lorien got posted on here.
No, i don't really have a general advice for that..all depends on what you want to build. I'd say start simple but as it grows you have to make sure your architecture stays clean, otherwise the whole thing becomes unmanageable. If you want to look at other big open source applications done in Godot look at Pixelorama and MaterialMaker (this one even got an Epic Mega Grant). There is also this list with great apps/pluings etc: https://github.com/godotengine/awesome-godot
It's still 0.x software though...for the 1.0 release i want add all these things ;)