1. change all text to uppercase (ref):

:%s/.*/\U&/

2. change all text to lowercase:

:%s/.*/\L&/

3. Add string (e.g., *) to end of every line (ref):

:%norm A*

4. Add string to beginning of every line:

:%norm I*

5. delete last character on every line:

:%s/.$//

6. Find your vi config file by typing:

vim --version

On Mac OS I see:

system vimrc file: "$VIM/vimrc"
     user vimrc file: "$HOME/.vimrc"
 2nd user vimrc file: "~/.vim/vimrc"
      user exrc file: "$HOME/.exrc"
       defaults file: "$VIMRUNTIME/defaults.vim"
  fall-back for $VIM: "/usr/share/vim"

You can now edit $HOME/.vimrc to create global configuration. e.g., to set tab spaces to 4 (instead of 8):

set ts=4

7. Turn on line numbering:

:set nu

8. list scripts loaded:

:scriptnames

More Tips:

• https://github.com/mhinz/vim-galore