Avoid firing on the spot and postpone to the next day. Document reasons for termination and be consistent with the termination process. Don't fire in retaliation for something the employee said or did.
Was the employee given feedback on performance, Counseling and opportunity to correct before termination?
Handle terminations in a dignified manner. Treat the employee with dignity and professionalism. Have witnesses in the meeting and document after the meeting.
Change password for email and computer access immediately. Any payout (salary, vacation, commissions, etc.) should be paid in a timely manner. Notify benefits provider for COBRA documentation.
Always get someone else involved that does not have emotional investment. In most cases that is HR or another manager, or your HR consultant.