<p>In short, you can’t do anything to assure your place at top colleges, especially as an international. The competition for internationals is even stiffer than for US applicants, and you will be directly compared to those students who HAVE gone to olympiads and have gotten internships. I don’t mean to discourage you, it’s just important that you have a reasonable understanding of your odds. I’m not certain how prestigious the certifications you have received are, if they are on a national scale than that will definitely help you, but you also say that they were given out by your school. If it’s just something within your school it’s still good, but will probably not impress as much. Do you have an interesting background? Any passions? If you can parlay those into activities that things that show initiative and affect your community, you will be a more competitive applicant. This also all assumes your test scores, grades, and course rigor is in order. </p>
<p>Also, as an international in need of aid, be aware your options in the US will be limited to the very few, very competitive schools that promise to meet aid for internationals, or schools where you qualify for substantial merit aid (these will likely not be what you consider top colleges, but I assure you they are still very respectable institutions you would do well at).</p>