I'm a believer in the old adage, "Hire slow and fire fast." It is so crucial to bring in the best employees; you must invest the time to get it right. Conversely, your company and all its employees are best off if those who are not performing--and can't improve--are let go quickly. But this is often easier said than done. For several reasons, it is common for managers to not fire employees quickly enough. Over the years, I've had to let my fair share of employees go--and I've watched many other managers do it, too. What I've learned is that there are ways you can make the process better for everyone, and there are ways you can undoubtedly make it worse.

Here are three pieces of advice for any business leader faced with firing an employee:

1. Don't hold back the truth. The most common mistake managers make is being uncomfortable--even afraid--to provide underperforming employees critical feedback. Poor managers are those who keep their concerns about an employee to themselves because they cannot have difficult conversations. I have also seen managers who fail to provide feedback just because it is easier for the manager to fix the problem themselves than it is to invest the time to teach an employee...especially if the manager deep down does not believe the lessons will work. Picture a head coach uncomfortable telling a player she is not playing her position correctly and not willing to invest the time to coach her up--and instead waiting until many games are lost before suddenly yanking the player off the field. That is a coach who would, obviously and quickly, lose his job. Well, it's the same with management. A manager's job is to put the best "players on the field," continuously teach them what is expected and how to do it--throughout the game - and take them out when necessary.

Continuously is the operative word here. You have to be honest and transparent as a leader from the get-go and coach every day.First of all, employees can't improve if they don't know what's wrong and how to fix it. Give them a three-strike timeline and a clear corrective course to follow. Secondly, if they do know what's wrong, and they aren't willing or able to fix it, you obviously don't want them anyway.

2. Don't not fire because hiring is too hard. I think it's rare that a manager ever wants to fire someone. As empathetic humans, we're hard-wired to give people second and third chances. And, frankly, in the short term it can seem less risky and easier to continuously coach an existing employee doing an important job than it is to begin the arduous process of recruiting a replacement--particularly when the market is very competitive.

But, if an employee isn't performing to your expectations, you can't let fear of an empty position keep you from doing what needs to be done. Remember what we were all taught: "Do not put off to tomorrow what you can do today." If you're going to have to inevitably replace someone, start sooner rather than later. The swifter you act, the easier the process will be. And, finally, do not to let yourself get into this pickle in the first place. Prepare your bench strength internally, so you've always got someone ready to step into key roles when the time comes.

3. Don't be a martyr. I've seen this a lot, as well. Managers are reluctant to fire an employee because they want to give them hope, or they don't want to force them out into a tough economy--so they feel like they're doing everyone a favor by prolonging the process. But they are flat out wrong. Never let someone waste time in a job for which they are a poor fit. In fact, this is the worst thing you can do for someone's career. Every day an employee spends working in a job not making you happy as a manager, they're losing a day at a job where they could have made someone else happy--and advanced their career by doing so.

And here is one more reason that retaining a poor performer is bad for your entire business: Why? Your high performers will see what you're doing, and they'll resent you as a manager. You're essentially showing them that the value of their work doesn't mean as much to you as it does to them, and that you lack the ability as a leader to guide people and make tough choices. This discouragement can quickly alienate your best employees and influence them to leave. That's a far greater cost than simply firing the bad apple in the first place.

In my experience, if you ultimately decide you must let someone go, both you and the employee will be better prepared for what's ahead if you act fairly, honestly, transparently, and quickly. You'll have provided ample warning and opportunities for correction, so you don't run the risk of someone feeling cheated or surprised. You'll have shown care for both your existing high-performing employees, and for the future career of an employee who wasn't a good match for your company. When you fail to demonstrate these things, people feel compelled to share their negative experiences on social media and sites like Glassdoor--which is bad for your employment brand. But the right approach can help solidify your company's reputation as a good place to work, even if the relationship doesn't last forever.