Getting fired/laid-off/made redundant is really rough. However you do it, know that the person you are firing will remember it forever. For some, it will be the worst thing that could happen to them. Take that into account when you do it.
The general advice on this subject suggests to make it brief, cut the small talk and basically say, Sarin, sit down. I have some bad news. Let them go. Tell them why. Tell them what happens next and cover everything essential: pay, benefits, unused vacation time, references, etc.
Here's some other factors to take into account to make it less awful for the person on the receiving end.
Earlier in the week means that people will have the chance to get right on looking for another position and reduces the chances that they'll spend the weekend in an emotional black hole. Firing someone at the end of the week, on the other hand, can mean less disruption to other staff.
Think about your language:
Don't say, I know how you feel. You don't.
Don't say, I'm sure you'll be fine. You have no idea.
Don't say, This is all for the best. It's not. It can be devastating. Just don't.
Don't fire half your staff and then realize you've made a mistake and need to hire them back. (Hello, Elon Musk.)
Use a modicum of emotional intelligence:
How the person you are firing will react is fairly predictable - especially when they have been an outstanding, committed, valuable employee - and even if they haven't.
Grief, anger, shock, denial. This model from HBR by Dick Grote is a good guide of how to respond to those perfectly reasonable human feelings like a human being.
Primary in all of those responses is the principle, acknowledge the emotion.
Seating: If you work in the same building, don't sit behind a desk when you have this conversation. Take down that wall. Sit on the same side of your desk as them. It conveys greater emotional availability.
Power: Getting fired, laid off or made redundant makes people feel powerless. Give the bad news and let the other person decide when the conversation is over. This is a way to give them back some power. It'll definitely take longer than sending a mass email but it's also how to act with kindness in really difficult circumstances. Make the firing part brief. Make the emotional support part long.
If you've been fired and my LinkedIn connections can be of service, please don't hesitate to be in touch. And if I can write you a reference, I will.