Well, this old fart has been flying for 42 years, and 26000 hours later, I managed to learn a few new things on a flight only a few hours ago!
If you think that you know it all, you're a dead man!
Perhaps the best "survival rule" that I could pass on is to always check all information for "reasonableness". Vital in this computer age (Garbage in, Garbage out = GIGO), perhaps even more so than in earlier times where human errors abounded, and we were constantly alert for them, maybe we trust the FMC a little too much?
Don't be hard on yourself, I've done far worse, and learn from it!
Happy flying (trust nobody, trust nothing)
Regards,
Old Smokey