The best way to study proportions, even if it's anime face proportion, you're still going to want to study normal human faces.
If you put the eye line in the middle/pupil of the eye and the top lip the overall spacing of facial parts isn't really that different! Just stylized.
The biggest difference is how wide and and round you want the face, but the part that helps the most of making a well proportioned face is the spacing of the eyebrows, eyes, bottom of nose, and top lip. Even if you make the eyes huge, as long as the center is close to the correct spot it reads fine.
(really gross sketch but i hope it makes sense)
There's no real tip to make it perfect, but just try and study real human faces to get a better anchor of facial structure, from there's it's easier to stylize.