How do you refactor?

Question

I was wondering how other developers begin refactoring. What is your first step? How this process (refactoring) differ if you refactor code which is not yours? Do you write

Answer 1

1. do not refactor anything non-trivial that does not already have unit tests
2. write unit tests, then refactor
3. refactor small pieces and re-run the tests frequently
4. stop refactoring when the code is DRY^* clean

^* DRY = Don't Repeat Yourself