The ISN has a great feature that will help save you time when creating a new email template!
Each email template currently in your ISN has a copy feature that allows you to simply click the copy button and that same exact email template is created in your ISN. This will allow you to then edit this copy and modify it to meet your needs.
Navigate to Email -- My Email Templates, and locate the email template that is to be copied
Click on the Actions drop down and select Copy Template
Once you copy the template, the new copied email template will appear at the top of the template grid. It will be named the same as the email template that you copied, however it will specifically say (copy). To make changes to this new email template, click on the Edit button:
Once you have made changes to the new email template, please remember to scroll down and click on the blue Save Template button!