Opinion from a recently accepted PHD candidate with full tuition waiver-
GRE-302 four years old score
MPH in united states with couple research publications and GRA work experience
First, come to the grounds in terms of your research interests. What topics interests you? Then filter the PIs accordingly. Develop your resume according to your interests i.e what research work related to your research area of interest have you performed or maybe work experience of any sort relevant to your research area of interest. All that a PI cares is are your interests corresponding to thier research interest? if not they would straight off say NO and reffer you to relevant department. PHD is all about research area of interest. PIS dont want to work with candidates in thier lab with completely different set of mind (research topic). Moreover you need not be sounding competitive as every lab has team work, so in your interview PI would specifically see in person or video calling if you are a perfect fit since you will be collegaues for atleast 5 next years.
Hope this helps.