What I started doing if I have no-one to proofread was to write my article, step away for a few minutes to a few days (depending on the importance and length of the piece) do something else, then come back with fresh eyes. You tend to see many things to improve this way! And now it's a habit.
But still, istakes happen, we are human atfer alll ;)
But always keep your brand image in mind.
Good idea, thanks for sharing that.