Start? Put time in front of the keyboard—to be a programmer requires nothing more than writing programs. Beyond that, it's simply learning and applying, just like anyone else.
I try to be deliberate in what I do and seek the simplest solution. In this, I hope, to avoid "seeing everything is a nail."
I learned a lot from Emacs, honestly, from core programming concepts, to how a community can survive and thrive, to the importance of software freedom.
I'm currently working through Nand2Tetris.