A lot of what Thomas talked about in his course is pretty similar to what I already do, with some tweaks and some additional tools. Here's what my system looks like. For some context, I graduated college a couple years ago and currently work as a software engineer. In my spare time I like dabbling in music and (lots of) rock climbing, which is why most of my task items here revolve around that.
I use the Inbox in Todoist as my dumping ground for immediately externalizing tasks that will be sorted later. When I do sort them, I dump them in one of a few buckets:
At the moment I use Evernote mainly to keep track of my climbing training schedule and my Impossible List. When I get my personal site up and running I plan on migrating my Impossible List over to that. Here's a neat Evernote trick: I like to organize my notes alphabetically, except for the most important notes, in which case I'll prepend the title with an underscore ("_") so it gets alphabetized at the top!
I try to keep my personal email at Inbox Zero as often as I can. I travel a lot (mainly for climbing trips) so I have a label for all my flights. Also nice to label all my Uber receipts in a Receipts label and have it skip my Inbox. My work email, though, could use a little help. Definitely not showing that here :)
I use my personal calendar to both keep track of events and medium-term personal goals. I color-code them depending on whether it's a personal event (blue) or climbing-related (green). In this case, I wanted to know exactly when each phase of my climbing training begins and ends, so I mark them down on my calendar.
There's also a feature in Todoist to create calendar events for which I find incredibly helpful. It can even store them as a separate Calendar in Google Calendar. I have it set up in my system, although I disabled my Todoist calendar for this screenshot for privacy reasons.
My work calendar (not pictured) is structured similarly, but for work events. I have it as a weekly-view instead of a monthly view since it's a lot easier to view my daily schedule that way.
Forest and Brain.fm for Deep Work
Now that my productivity system is set in place, it's time to hunker down and get some Deep Work done! I'm a huge fan of the Pomodoro technique to actually get in the groove of being productive, and my favorite app for facilitating that is Forest. When I'm deep in a coding project, I often like to listen to background music from Brain.fm. These two apps are a deadly productivity combo that can easily get me in the focus zone for hours on end.