In my neverending search for low action on my P-Bass clone, I finally worked on the nut. I have always been reluctant to do that, for some reason. I carefully filed down the slots until each string, when fretted between the second and third frets, had just a paper's thickness of clearance at the first fret. The difference in playability, especially on the lower positions, is amazing. I see a lot of threads about adjusting bridges and truss rods but very little about working on the nut. It wasn't hard but it requires a lot of care.