Can you disable toolbar by default in Finder? In Yosemite, opening folders in a new window by default is extremely difficult.
You can press CMD as you click (not optimal) or right-click/option-click the folder to open in a new window (not optimal).

The solution that seems to work best for me is to hide the toolbar whenever I open / create a new folder, because folders inside windows that do not have a toolbar will always open in a new window.

But the toolbar always reappears whenever I create a new folder. 

So, ideally, I would love to have it ALWAYS hidden by default, and on rare occasions when I need it (to look at external drives, or drag an item into the application folder for example), I would shortcut-make it appear, ta-daam.
This should work:

Close all open Finder windows
Open a New Finder window and arrange it to your liking.
From the Menu select View then Show View Options ⌘+J
Click the Use as Defaults button at the bottom.



Toolbar
Also, the View Menu shows many shortcuts to toggle view options.