- Extremely strong LORs, especially from profs, PI, and mentors that either attended, personally knew someone, or had previously taught at the institutes I had applied
- Writing a strong SOP for each program, clearly demonstrating that I knew what the degree would entail and that I had adequate preparation (especially in my case where my BS & MS degrees weren't in the standard fields of study that many of the applicants coming in had - though that may have worked to my advantage)
- Having 4.5 years of research experience. Even though some of the research was not in the area I'm going into - the transferable skills that I gained were viewed quite favorably. Plus by the PhD level, one should be self-motivated enough to learn material they had not previously studied if it would help with their research.
- Keeping a high GPA and doing quite well on the GRE. Now I list these points last since the typical applicant in the programs I applied to already possessed these qualifications and thus I feel the first three bullets held more weight in the application process.