Your job is different in the primary and secondary application
stages.
In the AMCAS personal statement you need to make a general
sell - explain why you will make a good physician. You must
tell your personal story in a compelling, unpretentious way.
Every application reader will be looking for something different.
My general rule is explain what why you love what you love.
For example, if you are serious athelete, talk about your dedication
to the sport. Explain how you have excelled. Make it clear that
these are the same qualities that will make you excel as a physician.
Explain why you want to be a physician in the first place.
What's your motivation, what are your goals.
This is also your chance to explain your unique situation.
If you are coming back to medical school from a career, explain
why you're making the transition. There are a lot of benefits
to making this transition - make sure you are emphasizing the
positive.
There are common pitfalls when you're righting such an essay.
You must walk a fine line between selling yourself and overselling.
While you should show your positive attributes - don't pretend
you're the best thing since sliced bread. Admissions committees
reading hundreds of applications a year, they can smell it when
you're blowing smoke.
Your job in the secondary application essay is very different.
Here you have to show that you are a good fit at the specific
school. For example, if the school requires a lot of medical
student research, make sure you show how that interests you.
Take the time to find out about the school to which you are
applying. Know the kind of student they accept, and the kind
of physician they make. If you match that profile, let them
know in the secondary medical school personal statement.