No matter how experienced you are as a manager it's never fun to give a negative review to an employee, much less fire someone.
I recently gave some advice to a colleague who was lamenting going into a performance review for one of his people who was delivering far below expectations. It was at the point where if major improvements weren't made soon he would have to be fired. My approach helped and he just e-mailed me saying the discussion went much better than expected, so I thought I'd share the leadership tip.
When you sit down face to face with that problem employee for the dreaded bad review, before you go into your documented laundry list of their problems, weaknesses, and failings - let them talk first.
There's a good chance they know that at least some bad news is coming and they'll feel better if they get a chance to articulate the problems right up front in their own words. An intro like "Bill, before I go into the details of this review, why don't you tell me how you think you've performed over the past X months" is a great way to kick off this session.
It will give your employee a bit of empowerment during an uncomfortable situation and may also give you some examples you can refer to later where you know they already agree with your assessment. If you have a formal document with your feedback and scores in writing, turn it over face down on the table during this first part of the chat. Then, when it's your turn to talk you can show the ugly details after the ice has been broken a bit.
In my experience this works just as well during a first negative assessment as when you have to threaten to put a person on that final warning before they will be let go. You may even be surprised that they are so aware of the bad fit between them and the company that they tell you they plan to resign before you have to go any further. Much better for both of you and for the company than a formal firing.
An important caveat:
I'm assuming you have a clear role document / job description for everyone on your team and documented goals and objectives to measure people against. If those aren't in place you have some ground work to do before you can be too harsh on someone and still be fair. At a minimum make an as objective as possible list of issues backed up by concrete examples. Focus on tangible deliverables and results that have been missed.
Otherwise you risk violating the No Surprises Rule with employees. One of the worst things you can do as a boss is catch someone on your team totally off guard with a negative review. Your people should always know where they stand with you and how they're doing on the job.
Give bad news early, constructively, and fast no matter how small the issue. Don't let problems with your people fester for a second! It's always easier to address something the moment it happens than bringing it up much later. And it feels absolutely terrible to have an employee say "but you never told me you weren't happy!"
Negative reviews are a necessary evil in the business world, but take courage in the fact that honesty is always the best policy when it comes to your team's performance. Hope this helps - your comments are welcome.