how to draw topology

one of the problems i have is how do we know who the topology of our character is going to look like so how can we plan our topology before we model the character are we just going to guess how things look how do we know how the polygons look like or how the bend and stuff. i got realy confused with that part of my chatecter. but after some reseach on the internet i came across this website.
http://students.autodesk.com/ama/orig/Curriculum/ICF2010/downloads/ICF_Level_2_PDF/ICF_Anatomy_Human/ICF_A_Anatomy_01_The_Character_Study_Sample.pdf
 this is a great website its pages from a book that teaches you how to create the topology for a character.

topology

i found this great website that gave me great knolege of how topology works and how crusial a good topology is to model a great character.
http://www.phungdinhdung.com/Studies_paper/Realistic_face_modeling.shtm

this will defenally be a website i will keep refering to when i start modeling my character