I have always been a fan of using a light meter to measure the light before taking a picture. For me, the light meter is a necessity to get the best exposure.
One thing you learn by using a light meter is how to really interpret the light because meters don't think, they only react. If I'm shooting an Asian model and the meter says F 16, and I later photograph an African-American subject and the meter says F 16, I know I need to adjust how I interpret the reading. I can't shoot both subject the same. The meter is giving me the correct reading, but it's giving me only an average reading.
For the image of Iman and the model, I would shoot at F 13, or 1/3 leas than F 16. For the asian model I may shoot at F 16. There are really no fast rules but one things for sure, you learn how to see light and how to adjust by using a light meter.
Alwaus dream big