Talk to your high school or college counselor about you desire to "test out of" college chemistry so that you can enroll in a higher level chemistry course, or other science course, when you enter college.
Take Advanced Chemistry in high school during your junior or sophomore year. If you decide (and your grades are high enough) to take this path it is important to do well, so don't be afraid to seek out additional help, such as a tutor, to help you succeed.
Take an Advanced Placement (AP) test or proficiency exam in college in which you demonstrate that you have mastered the subject matter that would be presented during a semester (or quarter) of college chemistry. Most general education requirements require that a student complete six to nine science courses to meet basic science core coursework. Make certain you speak to your academic adviser to confirm that you will receive credit for passing an AP or proficiency exam for college chemistry.