What you really should avoid:

• Notifications also are sent by email. DON'T SPAM YOUR USERS!
• Do not set notifications FROM the UI TO the UI. For example: If the user is in the webinterface and presses a button (SUBMIT) and is waiting for a response, the response should be shown in your plugin and not trigger a notification that implicitely is shown.
• If you have a script that works both interactive and in cron/daemon mode, make this script recognizing if it was called interactively, and suppress any notifications in interactive mode.
• Do not write HTML code to your notification $message. HTML code is not executed but shown in your notification.
• Do not append incredible long texts, like a logfile, to the notification. Use the LOGFILE parameter of notify_ext instead.

• As $package and $name may not be shown, write something about your plugin (e.g. the plugin title) into the message.
• If needed, use \n as linebreak. It will be converted to <br> if it is shown in any HTML functions.
• Try to use multilingual texts in the $message. Use LoxBerry's readlanguage function to first parse your language file, and then send the language variables to notify instead of hardcoded text.