Using the Stationery Pad option on your Mac will allow you to create a master template of a file. When you open a file tagged as "Stationery Pad", a copy of the original is always generated and opened. You can edit the copy and save it, and the original file remains untouched.
To make a file a template select the file and choose Command + I or right-click and choose "Get Info". This will open the Get Info dialogue window. Select the "Stationery Pad" checkbox and then close the Get Info window.
Now when you click the file a copy is automatically generated and opened for you.
If at some point you need to edit the original file, follow the steps above, but deselect “Stationery pad.” Then, open the file and make your changes. After you save your changes, repeat the steps above to save the document as stationery again.