Here are a few ideas on helping to get your children in the habit of writing about themselves.
Use a book that is engaging for the child. Have colorful and fun options for them to use.
Consider whether they should have lined or unlined pages. I have one child who is consistently drawing and doodling, so to help him focus on putting words on paper he has lined pages in his journal.
Let them have a selection of archival safe scrapbooking stickers.
Have themed journals- My children have a daily journal that they write in, they have a mourning journal where they write thoughts about their older sister who passed away, and as pictured above, they have a bikepacking journal. We are an avid cycling family and go on bikepacking trips at least once a year; we carrying the bikepacking journals in a plastic bag to protect them from the elements.
Encourage personal privacy and respect. No one is allowed to open or read anyone else’s journal without permission. This helps them write in a more honest and authentic way. They do tend to share some of their writings, but are not obligated to do so. Our only condition is that if, as parents, we feel that they are in danger or are endangering someone else then we may read a personal journal for information.
Modeling writing- write in your own journal while your children are around, share writings from your journal.
Share the journals and writings of others. If you have access to journals from ancestors consider sharing information from them with your children. I find it funny that in an ancestor’s journal he wrote only one line about his wedding the day he got married, but wrote over a page about farming conditions.