Lists and notes for sure. I am a huge fan of checklists and sticky notes. They keep me organized as well as giving that satisfactory feeling when I check something off or throw a post-it away. I also keep important tasks and appointments on the calendar app in my phone. I've tried planners, computer calendars, all kinds of stuff but I find having notes in my line of vision or alarms on my phone calendar are the best because they're more in my face and I don't have to open a program on my computer to get to the reminders.