> relentlessly applying a critical eye on everything I write and others write

Honestly, I believe that this is one of the best habits I've developed at my current workplace. We use Code Collaborator (a code review tool) for about 90% of all commits; I like using to get at least one pair of eyes on my code, but even further, I only even send out a review after I've gone through my own diff with a fine-toothed comb.