I my research, I found many places that talk about usability. But the explanations are very concise that you have to develop you own method in order to build a useful web site.
Though learning about usability gives me an idea how to begin my designs, I found a book that actually takes you by the hand and shows you step by step how to build web sites that can satisfy users.
The title of the book I recommend to read is DON'T MAKE ME THINK by Steve Krug.
Learning about usability is very important for me as wed page designer. I learned that a well-designed site is the one that satisfies its users without making them to overwork in order to find what they want. Even though the wed pages I have built are very simple, I try to practice usability by making the navegation very ovious and highlighting the most important parts of the page.
Other sites for usability