To save a file, we do <Esc>:w<Enter>.
If you add the following line to your vimrc, you can easily save a file by pressing F2.
map <F2> :w! <CR>
I just press ZZ to save and exit.
F2 is too far away from where I keep my fingers - I prefer the following:
map W :wa^M map! ^W ^[:wa^Ma
This makes W save all buffers in command mode and Ctrl+W do the same in insert mode.