As an employment lawyer, every new hire is a potential termination. Many managers wait too long to think about the potential future termination of an employee and don't create the documentation that they need to support an eventual termination decision.
By having a regular process by which you do documentation, as well as ongoing performance evaluations (formal or informal), you can create the expectation of performance and have the documentation to back up poor performance issues.
Documentation doesn't have to be complicated and, in fact, the more simple and practical, the better. Don't write things on the back of envelopes, don't scribble things that make no sense and follow the seven C's of good documentation.
Documents must be done close in time to the event to be documented. If you create the document two months after-the-fact, you lose details and credibility. It simply looks like you created it to help yourself, not to record the event. Date and sign the documents at the time you create them to avoid any confusion. If you think something might need to be documented, it probably does.
Use plain language that you and others will easily understand. Avoid jargon and abbreviations that have to be explained. Anything that has to be explained is a chance for a plaintiff's lawyer to convince the jury you weren't doing your job.
You're not writing the great American novel. Avoid the temptation to play Faulkner and stick to the facts. Don't editorialize and avoid those items that aren't part of job performance. However, always leave yourself some wiggle room. In discipline the reasons are never just "the following," they always "include the following" because there are always things you have to leave out.
If you have policies, stick to them. Don't make threats you don't intend to keep and treat everyone in a consistent manner.
Be specific and give examples. If they have been late six days out of the last ten say, "There have been various problems with your work performance. This includes absenteeism. As a recent example, you were late for work six out of the last ten days."
What would your mother, your minister or your Aunt Petunia, as well as a jury, think about what you are saying and writing. The final arbiters of these types of documents are third parties you don't know. Does it look fair and make sense?
Privacy is a mirage and secrecy is never absolute, especially when you may have to investigate a complaint. But everyone expects absolute privacy for themselves and none for anyone else. Keep the information as confidential as possible, but never promise absolute confidentiality. Don't communicate to anyone who doesn't have a reasonable need to know. Also don't create one document for several employees. Every employee should have his/her own document to protect the status of the personnel record. Don't list witnesses if you indicated that you would try to maintain confidentiality. Despite what employees may see on TV, they don't have a constitutional right to face their accuser in employment matters. Keep separate investigative file - not just stuff you throw into the personnel file.