What to do to improve my chances for Stanford, Duke, Harvard, and a few others?

I really don’t understand how/why you are picking these schools. It seems that you are interested in medicine, public health, biochemistry, engineering, and law all at once?? Most people would pick an area of interest, and then find schools that are good for that general area (ex: Engineering/CS → MIT, Caltech, Stanford, CMU, etc.), but you seem to be doing the opposite.

Please do more research on these universities and see what each offers. You might end up wasting hundreds of dollars on application fees with your current plan. I am saying this with your best interest in mind.

I wish you the best of luck with college admissions.