For face modelling its good to find a way to do it that you feel comfortable with, you usually start (unless u'r going to start off from a cube, but most people dont start from a cube or sphere) filling the main shapes out from the face you've got and getting a proper topology. I usually start to create the eye , very low poly until the few polygons that i have are properly layed out (lining up with the reference pictures). then i create the topology for the mouth also very low poly, same with the nose. After that I connect the nose geometry with the eye and the nose geometry, and try to get the basic topology right, then I add more polygons as i move on.


there are tons of video tutorials on youtube you can watch, thats how i learned

my advise is to search youtube to find a technique to lay your polygons out properly, and also search "topology" on google to see which important loops that you want to include