I just filled out my first one. As an incorporated sound mixer, I avoid W4's like the plague but inevitably I do a few jobs a year that I can't avoid it. You don't have to fill out sections 3 and 4, those are only if you don't want the tax withholding to be based on filing status and income. This is just one more reason to incorporate, but then again with the new California labor law passed 01/01/2020...