Beat up people in code review or interview;
Change other developers’ code without proper communication, or reasoning; worse, making the working code no longer work (sometimes to satisfying the “tests” 🙂
Learn, learn something everyday;
Acknowledge our own limitations: acknowledge our mistakes if applicable, we all do make mistakes;
In the same token, when we learn something from someone else, show our appreciation;
PS, also came across this piece “assertiveness from developers” by Jeff Atwood (@codinghorror), which I think is excellent. Essentially the point there is be a good developer is not to be a “nice person to everyone”. A good developer uses his/her best judgement, and speaks from his/her own mind, which includes saying something make other stakeholder uncomfortable (as long as it’s fair and honest statement).
And, slightly off topic, this one “Your Company Is Not A Family” from HBR (Harvard Business Review).