I've worked at companies during layoffs, and have been a manager at these companies as well (though fortunately never had to lay someone off personally). My advice:

- Managers should tell their direct reports personally, rather than delegating to someone else like HR. I still remember, unfondly, when one manager didn't want the burden of delivering the bad news and found someone else to do it.

- Give the people who will be laid off as much time as possible to send work emails, talk to colleagues, get taken to lunch, etc. As <steven2012> said, let them leave with dignity. Your employment agreement already prohibits misuse of corporate resources and criminal law prohibits theft of company property; as a general rule there's no need to have a security guard hovering over a desk.

- Write a letter of recommendation if your corporate policy allows and your employee's performance merits it. Give it to them in printed form and PDF. Don't merely offer to do it if they ask.

- As many others have said, do only one round of layoffs. Company morale can survive a single round. It may not survive repeated rounds, with nobody knowing when (and where) the next axe is going to fall.

- Communicate honestly with your remaining employees to the extent policy allows. The best managers will admit it if they don't know something.