How Sigmund Freud would perform a code review?
Knowing how to fix the code you review is just half of the work - the second one is giving this feedback so it'll be taken into consideration.
This will be a story of soft skills for engineers, and how I learned, the hard way, that even people you think you know, can't handle negative review. No matter how long you work together – it takes only one bad day for personality defense mechanisms to kick in.
I won't tell you how to trick your friends and coworkers into believing everything you say - it's not a NLP course, instead you'll learn how to fix yourself - so others will consider your feedback.