Not a PM, but beginning to take on a few duties for an internal project, and I'm quickly realizing how much of the job involves measuring and forecasting things

Not a PM, but beginning to take on a few duties for an internal project, and I'm quickly realizing how much of the job involves measuring and forecasting things that are immeasurable/prone to entropy. I always assumed PMs would ballpark things like Red/Amber/Green color codes and projections, but that "winging it" will only take you so far. The big lesson learned from a somewhat chaotic first foray into management was record everything, and leverage that evidence in every decision post kick-off. This requires more disk space than my brain has, so my note taking and organization skills were forced to go through an overhaul.