I am doing my first steps with TDD. The problem is (as probably with everyone starting with TDD), I never know very well what kind of unit tests to do when I start working in my projects.

Let's assume I want to write a Stack class with the following methods(I choose it as it's an easy example):

Stack<T>
 - Push(element : T)
 - Pop() : T
 - Seek() : T
 - Count : int
 - IsEmpty : boolean

How would you approch this? I never understood if the idea is to test a few corner cases for each method of the Stack class or start by doing a few "use cases" with the class, like adding 10 elements and removing them. What is the idea? To make code that uses the Stack as close as possible to what I'll use in my real code? Or just make simple "add one element" unit tests where I test if IsEmpty and Count were changed by adding that element?

How am I supposed to start with this?