The single most important lesson I learned from playing Dungeons and Dragons is to take notes. I started playing when I was in the Army stationed in Germany. Every soldier is supposed to carry a pen and a small notebook as part of his uniform. I wrote down many ideas. I transferred my ideas to larger lab notebooks. I still have those notebooks.
Today, I use a computer instead of a paper notebook. I own a Microsoft Surface. It is great for taking notes. Whenever I go anywhere, I take my Surface.
When I run an adventure, I open up a blank Word document and an Excel spreadsheet. I have a template in Excel to keep track of initiative and experience. I write down notes about the adventure in Word.
I found the graphic here