If you are writing the diary entries, make sure that you do the following things.
1. Write from your character's point of view (you are the character).
2. Explain in detail the thoughts, feelings, goals, motivation, etc behind major events/decisions.
3. Reflect on events/changes as your character.
4. Write at minimum 15-25 complete sentences.
5. Embrace your character. We should know by reading this diary that you understand your character and why he/she thought/did/reacted/etc. the way he/she did. This should be very personal for your character.
6. Proofread for spelling, punctuation, and grammar errors.
This following example is okay, but needs improvement. Reading it, you can get that the person writing this understood the events, but not the character. With a diary entry, we want to see that you understand the actual character. We want details from the book, but we want more focus on the thoughts/feelings, etc of the character. With diary entries, you have to get inside the character’s head. We don't want a summary of the novel.
Dear Diary,
Today I went to support group with Isaac at his request. He is really bummed about having to go blind from his surgery and all . So I thought it would be nice to go with him and stand by his side for support. Anyway, as I sat down waiting for support group to start. A girl walked in wearing worn out blue jeans and a yellow t-shirt. She had short dark hair and green eyes and was pulling an oxygen tank from behind. She was so beautiful I could not keep my eyes off her. I watched her every move. Patrick the support group leader started out with prayer. We went around introducing ourselves and telling everyone how we felt. It came around to that girl. I found out that her name was Hazel she told us she was “sixteen years old with thyroid cancer and mets in her lungs and she was feeling alright.”
At the end of support group I walked over to Hazel and asked her full name she said “Hazel Grace Lancaster.” She agreed to go to my house and watch a movie. My parents really seemed to like her. We went to the basement for a while and talked. She told me she loved to read. Her favorite book was “An Imperial Afflictions.” It sounded boring, but I promised her I would read it as long a she read one my favorite books “The Prince of Dawn.” We finally went upstairs to watch the movie. We sat a couple inches away from each other. We also ate the enchiladas mom made us for dinner.
After the movie she drove my car home with me riding shotgun. I played her a couple of my favorite songs from my favorite band. She had figured out I wrote my phone number in the back of the book I gave her. Hazel grace is so smart, Beautiful, and Clever. When I look at her I can’t help but smile. This was truly one of the best days of my life.