The AACOMAS PS doesn't give you any directions or what to focus on, unlike AMCAS. However, you could look at the directions given for the AMCAS PS section and go from there.
I focused my essay on how I got into osteopathic medicine, my shadowing/clinical experiences, and how these experiences solidified my reasoning for pursuing osteopathic medicine.
I would avoid cliche topics such as loving biology in middle/high school, or a devastating/life changing medical event that happened to you or a family (unless you can support and justify it with your academic/EC's). Your PS needs to show the actions you have taken to make sure medicine is the career for you. Actions speak louder than words..so make sure you mention key EC/research, etc.
Basically, anything you say needs to be supported by an example or something that can be verified elsewhere on your application. Make your PS consistent with the rest of your application!
If you feel like pandering to medical schools, focus on your compassion/empathy toward others, clinical experience(s), and leadership roles. Generally, medical schools love to see these qualities in their applicants. Also, check out some of your med school's mission statements, and align your experiences with their goals and values. If you can explain and justify why your shadowing/research/grades/volunteering matches their mission statements, you're golden.
I would also avoid explaining horrible grades/MCAT scores. I did have a horrible verbal score, and a downward trend in my grad school GPA, but I didn't mention it in my PS and I ended up getting 11 ii.....and no body asked about it during my interviews. Don't draw attention to negative things. Focus on your initiative, and positive experiences, and OWN your mistakes and explain how you learned from it (if you do decide to explain red flags in your app).
Hope that helps! 🙂 Good luck
