The combination of threads, remote-procedure-call interfaces, and heavyweight object-oriented design is especially dangerous... if you are ever invited onto a project that is supposed to feature all three, fleeing in terror might well be an appropriate reaction.

Given enough eyeballs, all bugs are shallow (e.g., given a large enough beta-tester and co-developer base, almost every problem will be characterized quickly and the fix obvious to someone).

Lisp is worth learning for the profound enlightenment experience you will have when you finally get it; that experience will make you a better programmer for the rest of your days, even if you never actually use Lisp itself a lot.

Smart data structures and dumb code works a lot better than the other way around.

Complexity control is the central problem of writing software in the real world

The Wesnoth devs are good but not exceptionally so, and we're weighed down by a crappy implementation language (C++). Nevertheless our productivity, in terms of goals achieved per hour of work, is quite high.

The next best thing to having good ideas is recognizing good ideas from your users. Sometimes the latter is better.