I'd say, having never really thought about it, you learn quality by coding the same thing repeatedly and optimizing it each time. So you can learn in that way.
Where to find friends who can review my code?
All of my friends don't know anything about programming or they don't code in there spare times like I do.
It is really hard to find someone who can explain what is bad about code design and what should I do about it or what should be "best".
And having a friendly reviewer is excellent!