The days of lifetime employment at a single company are long gone, so business leaders today need to make an extra effort to retain talent and foster employee loyalty.

Loyal employees are the heart of successful companies. When people feel fulfilled at their jobs, they go above and beyond to help the organization improve. They share expertise, resolve conflicts, suggest improvements, boost morale, help co-workers, conserve resources, and more. "Those behaviors make groups and organizations more effective -- sales are better, production loss is lower, everything is better," says Diane Bergeron, an assistant professor at Case Western's Weatherhead School of Management in Cleveland.

To become one of those lucky companies, take time to understand what your employees need and provide it for them. "As in any relationship, if you get what you need, you're more likely to stay," Bergeron says.

Loyalty is largely inspired by flexibility and individual attention. These four techniques can help you offer that to every employee: 

1. Invest more time in the hiring process. Hiring takes a lot of time, but a rigorous process pays off when you find the right person. "Person/organization fit is huge," Bergeron says. "If you're selective on the front end, you lose fewer people later." Well-matched employees are naturally more loyal, so retaining them takes less effort. 

As you hire, introduce the candidate to several people on your team, ask them to complete a project or share samples of past work, and screen for personality. "Make sure their values match the values of the organization," Bergeron adds. A good match will blend naturally with the others on your team, rounding out their skills and fitting in with the overall culture.

Related: How to Hire Key Players (Video)

2. Make your employees marketable. A good working relationship must be beneficial for both of you, meaning that employees need regular opportunities to enhance their professional skills. Many companies worry about investing too much in employees in case they leave, but you want to do just the opposite. "The more [employees] feel they can leave, the more likely they are to stay," Bergeron says.

Managers are the most important source of growth and inspiration. "The relationship with the manager is the number one predictor of whether or not someone stays [at a job]," Bergeron says. Make sure your managers are trained to inspire their employees, share their expertise, and offer opportunities for growth.

3. Allow many paths to promotion. Your employees' needs are ever evolving, so you can help them grow and inspire loyalty by offering opportunities for advancement tailored to their skills and goals. For example, many computer programmers want to move up without shifting into management, so tech companies often offer a choice between a technical or managerial career path.

Go one step further by helping an employee create a new job based on their skill set, or allowing them to rotate between different roles. "If people have the flexibility to tailor their job to their needs, they're less likely to leave to find what they need," Bergeron says.

4. Empower employees to make choices. Inspire loyalty by giving employees a sense of freedom and control. "When people feel that they're trusted, they respond to that," Bergeron says. You might let employees work from home when needed, make decisions autonomously, or adjust their work schedule to balance family. Those freedoms show confidence and help employees tailor the job to their needs.

"Trust is this basic component of society," Bergeron says. "Without it, [organizations] cease to function." Trusting companies have less rigid management, greater creativity, and higher employee satisfaction. They also inspire employees to go above and beyond, making the workplace better for everyone.

Related: Whatever You Do, Don't Not Delegate: Tips for Cultivating Great Employees