I find these following shortcut-keys essential.

Multiple cursors

Hold ctrl + using mouse to select where to add cursors.

Select multiple text (and automatically add cursors)

Double click to select the first + hold ctrl + double click other to select more

Select many similar texts (change variable name at variable place as one)

Place the cursor at the text + ctrl + D to select it, then ctrl + D again to select the next instance of the text. Repeat to select more.

Join line

ctrl + J at where I want to join.

Delete line (even blank line)

ctrl + X.

Move line (place the cursor somewhere in the line)/ block of lines (highlight them first)

ctrl + shift + up/down

Dublicate a line

Place the cure sure some where in the line, then ctrl + shift + D

Indent/ disindent

ctrl + ] / ctrl + [

Open file in current open project

ctrl + P, then search for its name.