Architecture for WinForms applications?

Question

I have started a WinForms project a few weeks ago and as I did not really know what features I wanted, I just added them along the way. This now caused a horrible mess where

Answer 1

Just start writing unit-tests for everything you can think of. As some pieces will turnout difficult to unit-test because of tight coupling to the WinForms, separate them out. Clean. Wash. Repeat.