This is my personal method, some leave them on, some shut them down. Just remember you asked!
First creed of computer use 'Save and Save Often'.
I remove my battery & run off normal power unless I'm traveling. Saves on battery life. Recharge monthly.
I save all documents to an encrypted jump drive that is also backed up to a second encrypted jump drive.
I make sure I'm logged out of all my financial sites then others.
I close all open windows/desktops (you can have up to 16 with a Linux OS).
I run Bleachbit (cleans&shreds all flagged apps/temp files/trash/clipboard/browser(2)history,,,etc.).
I go menu>quit>shutdown.
I remove & store all jump drives.
After screen goes blank I shut off my power strip (your laptop will use minimal power in shutdown).
Edited: If my home is broken into, a laptop is high target item that can be sold fast on Craigslist. I don't want personal information open to others.