These are huge time saving keyboard shortcuts. Commit them to memory, you’ll be glad you did.
Windows OS
Copy: Ctrl+C
Paste: Ctrl+V
Cut: Ctrl+X
Switch between App Level Windows: Alt+Tab
Undo: Ctrl+Z
Open Find: Ctrl+F
Mac OS
Cut: Command+X
Copy: Command+C
Paste: Command+V
Undo: Command+Z
Select All: Command+A
Find items in a document or open a Find window: Command+F
Print: Command+P
Save: Command+S
Open a new tab: Command+T
Take a screenshot of the entire screen: Shift+Command+3
Create a new folder in the Finder: Shift+Command+N