I started a Bullet Journal last night. I've tried a few times in the past, but haven't had success due to the difficulty in creating a good format in which to do it. I found one last night and it's really quite good: BulletJournal.com
The Learn goes into more detail about all the specific scenarios in which to use the various symbols, but here's a quick rundown:
• This is an incomplete Task • Tasks can be nested x This is a completed Task (you X over the dot) - This is a Note ◦ This is an Event • Anything can have a Task - Or a note
For a fuller explanation, they have a quick video on setting up a notebook:
I'm really excited to put it into practice; I've already used it several times since I started and am looking forward to using it to be more organized.