Basics

Open file

:e path/to/file

Working with sessions

Create new session

:mksession ~/mysession.vim

Load session in existing window

:source ~/mysession.vim

Run vim with session loaded

vim -S ~/mysession.vim

Lines

Move line up and down

:m -2  # 1 line up
:m +5  # 5 line down

Misc

Surround word by (...)

bcw()<ESC>P