How do I keep good employees and maintain working relationships at all levels?

First of all work environment and company's culture , Employees are Humans we have to recruit the right one for the right position but also we have to look for employees who can exactly fit our company's culture ore the company's culture fit them .

Second we have to maintain this employee not just hire him, make him feel that he belong to this company and the company needs him as well all of that with compensation and benefiets , motivation , appresial system , welfare party etc

You can keep good employees by training them  to devlope their skills continuallly and manitain working relationships at all levels by holding meetings with them periodically to find out their complaints and work out to solve them.

well you can evaluate the result of their working , also notice the imrovements, time management, attitude towards work,firm and co workers you can use some of the organizational tools for this , 

and please know that the satisfaction of the employees is a big thing to consider when you want to maintain that relationship , providing cost effective programs and benefits could help that 

Thanks

Follow these two steps

• Keep your relationship with them as a colleague not manager.
• Keep motivating them.