Try not to do the most stupid thing
Stop trying to get people to be smart and start from the other end of the scale. Try and stop them doing the most stupid thing. This works particularily well with smart people who are usually so busy being clever about stuff that they regularily do the dumbest thing in the playbook while engaging in some really smart piece of activity.
So, get your smart people to start thinking about the stupidest thing they could do, and then get them to not do it!