Understand the purpose of your writing and the intended audience. Is your story a retelling of your experience living in the woods for a year? What is your intent in writing this story? Who will the story appeal to and what will it tell them about the experience?
Avoid a simple listing of events. For example, do not write "I went to the stream. I got water. I returned." A narrative should let the reader experience your journey through your eyes. This is commonly referred to as "Show, don't tell." Keep your eyes open during your experience for the little details that you would otherwise miss. Every moment of the experience must be treated as a research opportunity.
Choose the tone of the writing. Ask yourself whether your work is meant to thrill the reader or make them think. A philosophical work will be paced much slower, with much more inner reflection, than an action narrative filled with adventure. The tone in a journal will be dictated by both the cause and the events of the experience. For example, were you living in the woods to escape and contemplate society? Did you encounter danger such as wild animals or forest fires?
Choose a tense for your narrative to further sharpen the tone of the narrative. Is the narrative being written as a reflection on the experience, or is it a day-to-day telling of the events as they happen? Writing the events in present tense adds a sense of urgency to conflicts and challenges, making for exciting reading. Writing in the past tense will create a reflective, critical voice for your writing and allow you to comment on the experience more deeply.