It is very important to assign appropriate log levels to each of the log statements.

Logging should also be considered in a cluster environment. We can use the same type of log files, with the cluster node name as a suffix to the filename. This will prevent the log entries from being overwritten or wrongly considered when analyzing logs.

Building log files impacts the application's performance. If an application starts logging every minor piece of information, the application's performance will be slow. We must ensure that the size of the log files and frequency of writing log entries are low.

All exceptions, except for validations and input errors, must be logged. The exception messages must be logged in a way that highlights the problems clearly. The best practice is to let the framework log all of the exceptions.

Logs must be user-friendly and easily parsed. Logs can be used in two ways. One way is that the users read the logs to build understanding. Another way is that the utility programs parse the application logs, based on the log formats, to filter out unimportant information.

Every log entry must be different from other log entries, though they represent the same information. Every log entry can have a unique identifier, most often based on the timestamp, which can be used to differentiate it from other logs.

Sensitive information must not be logged in log files. Passwords, credentials, and authentication keys are a few examples.