The basic idea behind a bullet journal is that you write down very succinctly, what is going on in a day. This takes the form of to do items, events, and notes. Different types of bullets indicate a variety of things. If you're really interested, I suggest checking out the website above.
The reason it's working well for me is that I schedule to do items. I don't just write them down in an ambiguous list, but I put them on a specific date. Also, if something doesn't happen, then I have to move it by manually writing it down by hand onto a new date.
I also like that it forces me to once a day sit down and reflect on the previous day and prepare the next day. I like to leave it on the kitchen table at night so that it's waiting for me in the morning when I have breakfast. It really helps me prepare for the day and get organized so the things I need to do get done.
Hopefully this method lasts for a while. I'm a fan of it.