That depends on what you are modelling.
If you are modeling a human then there is a general set of rules.
If you are wanting to model a person that does not exist I would suggest using a ref of another person and then work from that.
Try to find some images of people on the web. Use Google image and ask for person profiles, refs, textures, etc...
You will no doubt find alot of images that will help.
OK you asked for eye sockets so I'm guessing your asking for edge extraction.
face modeling
( you tube it ) ...seriously lots of tut vids (not anim8or but good enough)
Make the general shape of the eye, as a set of faces that match the eye socket then use the edge extraction tool.
( this is probably the best tool I have recently learned to use)
