The PSAT/NMSQT focus on your skills and knowledge and measures:
What you learn in high school
What you need to succeed in college
Junior year, this is the year that you are considered for the National Merit Scholarship competition
Sophomore year allows you to get the feel of the test
Freshman year gives you a good baseline of areas you need to work on
Take challenging courses
Do your homework
Prepare for tests and quizzes
Ask and answer lots of questions