They know what salaries you're giving to new employees, and they know what others doing the same job across town are receiving. Nothing makes an employee feel more valued than an unasked-for raise. No one likes to work in an environment where they're going to get scolded. The surest way to drive employees out is to berate them. Instead, when something doesn't turn out the way you hoped, instead of looking for those responsible, concentrate on understanding how to avoid the problems in the future.
Employees feel a stronger sense of ownership when they actually have ownership.
Various methods enable employees to have a longer-term stake in your company, including stock options, employee stock ownership plans, profit sharing plans. Enable them to grow. After awhile, even the best employees get bored doing the same job. If the only way they can grow and change is by leaving, then they will. Instead, invest in your employees.