The biggest transition for me when I started college was learning to get organized. There was a point when I couldn't just remember everything in my head. And having to constantly keep track of things was distracting me from whatever task I was doing at the moment.
So I tried various forms of todo lists, task trackers, and productivity apps. They were all discouraging because the things to do kept getting longer, and there were too many interrelated things like past meeting notes, calendar appointments, idea lists, and lab notebooks, which were all on different systems.
I gave up and started just tracking in a single text file and have been using it as my main productivity system for 12 years now. It is so essential to my work now, and has surprisingly scaled with a growing set of responsibilities, that I wanted to share this system. It's been my secret weapon.
Prerequisite: A calendar. The one outside tool I use is an online calendar, and I put everything on this calendar, even things that aren't actually for a fixed time like "make a coffee table at the workshop" or "figure out how to recruit new PhD students"