What is the best way to secure a position into Harvard?

Short answer: there is no way to secure a spot unless your family donates millions of dollars to the school, and even then, you need to be academically competitive.

There are literally thousands of outstanding high school students who apply to Harvard every year. Harvard rejects many, many talented people - in fact, the admissions staff has even said that if they threw out all the applications they accepted, they would be able to put together a class that was just as qualified from the rejected applications. You need top grades in a rigorous high school curriculum, stellar SAT scores, leadership/awards/demonstrated service in your extracurricular activities, and you need a good dose of luck on top of everything. Be a leader in your school, get strong recommendations from your teachers, and write essays that reflect who you are - that's about all you can do. Once you're done, just sit back and let things take their course. If you're rejected anyway, rest assured that it was most likely not due to any weakness on your own part. Harvard has said that the majority of its applicants are well-qualified and able to handle the work. But if you are a competitive applicant, you will surely be admitted to at least one of Harvard's peer schools (e.g. Yale, Princeton, Stanford), which is not a bad option to have at all.