The first-person mode isn’t for all of us. It can be hard to carry a whole narrative on the shoulders of a character’s personal perspective; you need to pay attention to the character’s voice while still having that character tell us all the information we need to follow a story.
That being said, I still think it can be helpful to write in a first-person perspective now and then. In particular, I think it can be helpful to craft a diary entry for a character – or two, or twenty, if you feel the need. They don’t have to be long, and they don’t have to follow any particular format. Indeed, you might find that one character jots down lists and bullet points, while another prefers more conventional paragraphs. Some characters might keep careful track of the weather, while others might be particularly concerned with another character’s behavior toward them.
You may even find that a diary entry turns into another, and another, and another until you have enough material to fill a book. This is great, but you must be careful to edit your diary entries so that they follow some sort of plot. Make sure that you leave out entries that take us too far away from what is happening in the narrative you’ve created. Cutting out excess wording can be an unpleasant experience, but it’s sometimes necessary to transform this writing exercise into a marketable narrative.
Although I have written longer stories in a diary format, I prefer the third person for the vast majority of my work. Diary entries, for me, are more of a tool I use to get a good feel for a character. It helps me develop their speech patterns, the kind of metaphors they use, and the things they notice about the world I’ve built for them. It seems fitting that for the vast majority of my readers, these diary entries will remain a bit of a secret.