Hotkeys or (Shortcut Keys) or (Keystrokes) are essential to learn because they speed up the time it takes you to perform a sequence of tasks. Often what works in one type of software will perform the same task in another. Here are a few i find very useful:
“F” is for Frame (centre) selection but i prefer to call this Focus, So when you select an object either in the scene view or in the Hierarchy window pressing this key will focus in on the object, this is the shortcut key that i use the most.
On the toolbar (Top, left) there are 5 small square buttons
Q = Pan
W = Move
E = Rotate
R = Scale
If you are movings and rotating an object around your scene it is useful to switch between W & E, Personally i don’t use Q Pan because my middle mouse button performs the same function.
Cmd+C, Cmd+V (Mac)
These are universal shortcut keys and work with most software but in Unity i find this very useful if i want to copy an object or many objects from one scene into another.