Personally, I use a combination of Google Calendar/Microsoft Outlook on either PC/smartphone, at work and in my personal life. (I find that these work for me, they may/may not work for you). I use the calendaring functions to keep track of appts/tasks/scheduling. Their contact functions allow me to keep an address book, I also have access to a tasklist and note taking functionality. For someone who has ADHD most of his life, they are a GODSEND. But regardless of what I use, you need to find what works best for you, and it likely will take time/effort. (It took me most of my time in middle school/high school to figure out what worked for me.