Purchase a notebook with divider tabs. Four divider tabs is sufficient for including most of the information you might want to include in your notebook. Label each of the tabs. Example tabs include "Story Ideas," "Title Ideas," "Character Sketches" and "Things to Accomplish."
Keep track of any ideas for stories in the section marked "Story Ideas." You might want to include a brief synopsis of each story idea. Under the appropriate category, make a brief character sketch of any characters that come to mind, either from observation or from your imagination. Include potential character names and descriptions of your characters.
Devise a system that you can use to cross reference the material in your notebook. If you have a character that might fit well into a story idea, indicate the character with the initials of the story title. Place the same initials next to the story title and any other information in your notebook relating to the story. Later, as you go through your notebook, you'll see any notes marked with those initials and know that you want to use each of those elements in the same story. You could use colored highlighters to mark related notes or letters of the alphabet. The key is to use a system of cross referencing that will let you easily identify related notes in your notebook.
Consider adding a section to your notebook of clippings of news stories that may spark a story idea and photographs of places you may want to use as a setting in one of your stories. A notebook with pockets is ideal for including this material. Photographs are an especially useful addition because they can help keep in your memory how something looks until you get down to the business of using them in a story.