Finder default window
I used this "trick" on Mountain Lion and it worked well for me.


  Create a new folder on the Desktop (CMD+SHIFT+N), open it, select
  View-View Options (CMD+J), set the window to your desired size and
  type view (either icon or list view: I prefer the latter), select
  always open, and then click Use as Defaults button. That should retain
  your setting and every other folder you open for the first time should
  also inherit those settings.


Source (Apple Discussion)