If you're not initially placed in the courses you want, don't give up! Advocating for yourself is a valuable skill.
Request a meeting with your counselor and/or the teacher. Be respectful but persistent:
"I understand the normal placement criteria, but I believe I'm ready for [course] because [specific reasons]. I'm willing to [put in extra effort/take a placement test/sign a contract] to prove I can handle it."
If the answer is still no:
Focus on final exams
Freshman Year
No room for slipping
Junior Year
Maintain grades through end
Junior Year
Attend summer school
Freshman Year
Submit selective summer apps
Sophomore Year