Here are some suggestions drawn from our own experience, the research, our clients and trainers around the world… 

• Use the language of the training when giving feedback. (It’s essential.)
• Provide coaching for one or two staff members at a time.
• Provide a workshop refresher. It’s best done internally, but ensure that whoever is leading it is not providing a watered-down version of the key concepts.
• Put up posters reminding everyone of the key ideas from the training.
• Ask team members to provide brief presentations on a particular aspect of the training.
• Include a key training point in every staff newsletter or e-mails to the whole team.
• Organise ‘master classes’ for the team members to share ideas and develop their skills.
• Develop champions to keep the momentum going (particularly appropriate for customer service training).
• Create opportunities for colleagues to teach others what they learned in their training.
• Develop a speakers’ club for those who have learned presentation skills. One of our Crown research institute clients has an in-house Toastmasters club.
• Praise, effort, determination and resilience. 

Also see our article How to give feedback that really works.