Kelly Sutton with good advice on code reviews. Hard to pick a favorite. I like all the stuff about minding your tone and getting everyone involved, but I also think the computerization stuff is important:
If a computer can decide and enforce a rule, let the computer do it. Arguing spaces vs. tabs is not a productive use of human time.
Re: Tip #6: it's pretty cool when the tools you use can help with that, like this new GitHub feature where code suggestions can turn into a commit.