How to do a clean install of macOS Sierra

[iMore.com]

Feel like you need a fresh start with macOS Sierra? Do a clean install!

Full story from the iMore Blog...

 

[Jayzen]

I am going for the clean install on my mid 2012 Macbook Pro. I have big concerns re restoring files/media etc. from my Time Machine External drive back. I just replaced my Hdd with an Evo SSD 250 Gb. I backed up El Capitan using a Sata cable method then installed my new drive. All went great however I did not partition the drive to 2 or above. So I am concerned about what will happen when I do a USB Bootable of Sierra if I will have that back up of El Capitan to pull important music I've written from.
I know I can Partition the existing 2 TB External to have additional volumes. Just not sure whats going to land where & the order to perform the clean install?
Any thought would be greatly appreciated. Oh also I apologize for the double post. I just joined up here and want to make sue my post is scen in the appropriate place. Which it may still not be. Sorry.