Hello,
I am a photographer and videographer but I know almost nothing about illustrations. I will be greatful if you tell me how to start. First I will make some rasterizations of my pictures but I'd like to know the best workflow regarding Adobe Illustrator and agencies: which kind of file to save so every/most of the agencies accept it? What resolution/size to set and so on?
For example I know that if I use Photo-JPEG, 1920x1080 and 24 fps for footage file it will be accepted everywhere.
This kind of information I need about illustrations.
Thank you in advance!

Each of the agencies has information about what types of formats and sizes they accept.