When programming, automatic line wrapping can be a little obnoxious because even if a piece of code is hanging past the recommended 72/80 column width line, you probably don't want to immediately break it; but if you're writing a text document or an email message, that is specifically the behavior you want.
The value of format-options will drastically change the way Vim behaves, so I highly recommend keeping it displayed some where you can reference it quickly. I use:
You probably have a statusline of your own; just add that small snippet minus the ellipses in somewhere convenient. For further good measure, I explicitly say set fo-=t in my vimrc, to prevent myself from being surprised (since I do primarily coding in vim).
autocmd BufEnter * highlight OverLength ctermbg=darkgrey guibg=#592929
autocmd BufEnter * match OverLength /\%74v.*/
This will highlight all characters past 74 columns (tweak that number as desired) in dark grey (tweak that color as desired), and is a nice visual cue when auto linewrapping isn't turned on when you should think about breaking things.
thanks to http://blog.ezyang.com/2010/03/vim-textwidth