Some good points here....
Verbalising everything?
Don't know if they still do it, however the USAF used to talk all the time in a multicrew environment. Cant be all bad?
Airmanship
Is everything from cleaning the a/c when you have finished with it, inside and out - a rag over the cowl goes a long way, cross the seat belts, use the chocks and the control lock/s and always look behind when starting and/or doing a run-up. Set the instruments/radios for the next flight if you know where it is going. Lift the wing in a highwing a/c before turning in that direction etc etc.... and a thousand and one more! Treat others and the system as you would like to be treated. And of course double check all entries before you hit the Enter button!