I've tried using todo lists (physical and apps) but, as soon as they're not in front of my face, I forget about them. Lately I've been putting Everything in my calendar app. I have a widget on my phone home screen that tells me what's next so I always see it and regularly tap it to see what's on the day and the rest of the week.
It's not just appointments. I'm also putting tasks and reminders on there which are typically "todo" list things. Centralized, just a glance away.
It's also becoming an aid for journaling? I'm putting in shit just to remind myself what I've done socially and privately throughout the week.