I'm in a love-hate relationship with Unity's Asset Store. I love it madly because of the huge number of libraries I can use to avoid reinventing the wheel.
On the other side, I hate it because of this:
I mean, of course, the fact that there's not a standard way of organizing a Unity project. There are some special folders, but no one has said "Hey! Let's put every external library here!" There are some epic examples here, like a folder named "Src" that tells us absolutely nothing about its contents, or even worse, another folder named "root".
I've experimented with multiple ways of organization while developing my projects. My first attempt was creating a Libraries folder where I put everything that wasn't self-made, and then using root subfolders to organize my own code. I recommend using this system only if you are a masochist that likes wasting your time and are willing to fight the load of problems you'll find when moving libraries from their folders. These problems, by the way, are usually caused because so-called programmers love to hard-code routes. However, we're not here to criticize horrible decisions, but to fix this.
Our Assets folder root is lost, so we don't want to mix our content with all the crap that will unavoidably end there. Once again, I speak from experience:
So let's forget the root folder. It's not for us. It hates us, and we hate it, so there's only one solution: Creating a folder where all of our project will go:
Even if it's not necessary, putting an underscore before the name to make it be the first folder in the hierarchy will save one or two seconds every time we are looking for it, and, as we programmers know, removing one or two instructions from a loop that runs millions of times is a great optimization. But let's go even further.
What is inside this folder?
Some of these folders are exclusive to this project. It's not a bad thing to deviate from this standard to adapt it to the particular needs of a project. However, two folders that should be always there are Scripts, Tests (Test your games, love the Unity Test Tools. We'll talk about this some other time), and Editor, because I've yet to see a project that doesn't benefit from some customized tools.
I believe Unity needs a standard for Asset Store library organization, even if it is just everybody using an AssetStore folder or something like that, but, meanwhile, we'll do whatever is in our hands to keep our projects organized, becoming better and more productive developers.