Dear Neeraj,
Blue collar or otherwise, teach them about the quality aspects of their job. How customer satisfaction improves with the help of quality work and how it in turn raises the organisation's competitiveness is very important.
Secondly, measure the ratio for suggestions of process improvement. You may teach them how to give suggestions in order to improve the process or product improvement.
While you may have temptation to conduct training subjects like positive thinking, personality development etc, trust me, it will not have any bearing on their job. Please take it for granted.
Generating quality consciousness at the grass-root level is very important. Most of the company's trouble originate because of poor quality. If they are able to understand cost of quality and cost of poor quality the better!
Thanks,
Dinesh Divekar