Where are you currently attending school? Why do you want to transfer to another school? What do you wish to achieve in the new school? One of the reason to attend schools in the U.S. is to establish friendship and networking and if you were to switch half way, you will be making friends all over again. If you are already in a decent high school, they must have counselors to help you either transfer to another high school or prepare you for college placements. I would explore that service and seek their advice.