HR needs to constantly collect feedback from the employees. These feed-backs can be on simple items that could be done through a poll or could involve more complex feedback requiring a survey. The result of this feedback would need to be collated and reports generated. Based on these reports, assertions need to be made and follow-up actions (if any) should be taken up.
A well known fact is that employees working on a specific areas, are a great source of information on improvements that can be done and processes that can be streamlined, or made efficient by removing certain bottlenecks or doing things differently. A good HR would ensure that this channel of communication is kept open and active participation of the employees is sought. A good HR practice on employee engagement is to wish employees on their birthdays, marriage anniversaries, etc.