Necessities of a bachelor's student trying to apply for PhD in Applied Math
my qualifications: I am currently in final year of my bachelors degree in EE in a 2nd gen IIT, cgpa 8+ (gpa 3.2+), 10/10 grade in Real Analysis, 9/10 in Linear Algebra, Complex Analysis and Probability & statistics
I am planning to do a PhD in applied math from a possibly top 20 US university. I will be writing my GRE Mathematics Subject test this november to boost my profile as much as I can. I also interned at a MnC as SWE intern this summer. Extracurriculars I have as of now are I play football for my college team, play guitar on my own.
Apart from these what all exams and foundations I have to build to maximize my chances of getting accepted? I have heard about IELTS, TOEFL, SAT, etc admission exams. Also I have heard that you need to do "cold mail" stuff to profs of the university you want to study in.
Considering these can someone who has already gone for PhD write a streamlined workflow of all the things I need to do before officially applying.