I went to a really interesting talk a while back on food safety culture. It raised a really important point; everyone is really bad at washing their hands. You then take your average person in the street with 25 years of shocking hand washing experience then expect them, after a 5 minute training session to be great at it. It's not going to happen.
So this is what I am working on.
We train people before they walk through the door. We importantly explain why.
We then train people face to face, get them to demonstrate.
We have posters up in the vicinity of hand washing stations.
What we're moving onto now is some quick 4 minute recap training sessions, mostly by video as reminders.
If there are specific issues we may take groups away from the shop floor to do something more intensive.
We're also training staff not to walk past a colleague washing their hands badly.
All of this is verified by auditing, CCTV (we watch back the feed sometimes at random and if anyone is seen not washing their hands at all they are disciplined).
So it's the typical technical thing. You set the standard; communicate the standard, train it, verify it, put in corrective actions, change the standard if needed and keep on and on and on... the thing which that talk on culture taught me is training is never a one off activity.