[baldfat]

vim file_foo

press i for interactive and make changes then press :wq

:) I have that embedded in my brain after all these years.

[gargravarr]

You forgot ESC after making changes ;)

nano file_foo

make changes

ctrl-O-Enter - save ctrl-X-Enter - exit

Simpler, I think?

[eximius]

Don't even need the ^O, it asks if you want to save on exit if there are modifications.