Use the journal as a way to reflect on the day. This can include interesting (or even mundane) things that happened to you or to people around you. You can also note any unique ideas or thoughts that you'd like to keep for posterity. A journal about your daily life can add context and meaning to each day, at the same time preserving memories while they are still fresh.
Keeping a journal beside your bed is a good way to record dreams from the night as soon as you wake up. The longer you wait to write the dreams down, the greater the chance you will forget them, so do it while they are still fresh in your head. You can also include thoughts about what the dreams meant to you.
Memories of your childhood can be recorded in a journal. Write in as much detail as you can about these memories, including the content of the memory, how it made you feel, what your surroundings were, and who was with you at the time.
Writing about your favorite vacations not only helps to develop creative writing skills by getting you to write a detailed story, but also allows you to relive what made the vacation so special and memorable. Write about where you went, who you went with, and interesting sights and events that you experienced on the vacation.
One creative writing topic for a journal is a narrative of how you picture your life when you "grow up." This can be a topic for either children or adults. Children can tap into their creative sides to imagine a grown-up world where they are firemen, professional athletes or astronauts. Adults can use their real world experiences, as well as dreams for the future, to imagine where they would like to be in the years to come.