Phil Booth shares some recommendations:
First, let’s establish what the point of code review is and also what it isn’t.
The number one, most important reason to review code is shared ownership. “Ownership” can be tricky to define in code terms, but mostly it’s a feeling. It means you understand the code, that you feel empowered to change it and the responsibility to maintain it.
Click through for Phil’s thoughts on what makes for a good code review. I’ve found that the over-the-shoulder code review isn’t nearly as effective as you’d hope, and a proper code review can take a considerable amount of time, up to hours or days for a large change.