Let clients dictate the pace of work
Employees don't like it one bit if their managers put the pressure on. They are much more likely to work hard and long hours if they know it is because of customer demand.

Small freedoms
These can be as apparently insignificant as moving the desk, controlling the office temperature or even opening windows. It all spells out some degree of environmental control and respect for the workers.

Plenty of people contact
Staff are much happier if they have a lot of contact with other people – if this isn't the case, think of redesigning the job to increase this … you don't want to end up with antisocial misfits.

Employ more women
Women, statistically, have a tendency to be happier than men.

Don't employ commuters
People who live close to their work are far less stressed. Stands to reason, with train and Tube failures.