Automate as much as possible to make it difficult to make a mistake. Check lists are a good start. Keep aggregate stats on overall quality and at regular team

Automate as much as possible to make it difficult to make a mistake. Check lists are a good start. Keep aggregate stats on overall quality and at regular team meetings set goals for improving the stats of the group overall in small increments. Give praise of each improvement and then make a new goal. Privately keep stats on individuals if there is someone who is an outlier in terms if mistakes talk with them privately about how they feel about the job in general and how it might be effecting their mistake performance if they don't improve you might have to find a replacement. Realistically though there is always going to be some number of mistakes unless you have both automated double checking and a second human in the loop checking everything.