I keep a bullet journal, which is mainly for journaling and long-term planning.
Some days I write a list of tasks on a piece of paper.
I put events with a definite time in my calendar (add with Fantastical, review with Calendar app, Week Cal + Fantastical on iPhone, Calendars 5 on iPad).
I put "someday" tasks and tasks that have a definite due date in Things on Mac and iOS (the new version is one of the best pieces of software I've ever used). The new Things also integrates calendar events into the "Today" view, which is quite useful. But I don't look at it every day.
Previously I used "2do" with "smart lists" corresponding to a priority matrix ("important urgent", "important not urgent", "not important urgent", "not important not urgent.") It was a bit too complicated and I switched to Things when the new version came out a couple months ago.
I also used to have a daily checklist in 2do, but after it became habit, I found I didn't need it anymore. I highly recommend a daily checklist for anyone recovering from burn-out, depression, or similar.
I've just switched to doing high-level planning in a "Master Plan" document in Quip. It's already quite detailed and covers most aspect of my life.
Otherwise lately I organize my days into 3 or 4 timed 1-2 hour focused work "zones", with as much ceremony as time affords, to the point of making special drinks, listening to specific music depending on the theme, and lighting candles.
I'm also experimenting with 3 10-minute open-ended thinking periods per day, for which I have alarms set in my phone.
The latter two habits have been very effective. I'd tried Pomodoro in the past, but I find that ceremony is important.
That sounds pretty exotic, but the major insight from the past 10 years of trying things is that finding the one right system is a fool's errand. Trying many different systems – the simpler the better – and letting them evolve naturally works best for me.