In the past two years I have been teaching singing online. I usually tailor my classes based on students' needs.
A basic structure of the class would be me giving you vocal exercises, listening to you sing and solve the problem I hear, working on songs etc.
I will start from the basics like air flow and breathing to placement( resonance) and vowel modification, posture, how to maintain your voice( voice care) etc.
As a student I have gone through so much trial and error to learn, so I have been frustrated at some points, but the key is consistency and being patient.