Today's subject can actually be a Do and a Don't.
DO: Review the Proof Carefully
When you submit a job to a printer, they will usually send you a digital proof for approval before the job goes to press. Make sure you check every detail on that proof - check for spelling, punctuation, alignment, fonts used, missing words, things that may have jumped off the page, etc. At OEX, we do our due diligence to ensure the accuracy of the proof, but human beings are flawed and they do make mistakes, despite their best intentions.
DON'T: Assume that everything is OK and just sign off on the approval form.
Proofreading is a shared responsibility - what is shown in the proof represents what will be printed. The printer is not responsible for errors if the proof was approved with the errors in it - in that case it is your responsibility and you would be charged for the reprint.
One word of caution: Monitors can't be used for accurate color matching. Monitors are RGB and printing is done in CMYK, so the colors on the final printed piece won't match exactly to the proof that you saw. To confirm colors, the Pantone Matching System (PMS) should be used whenever possible.
RGB vs. CMYK
The bottom line: Check, double-check and triple-check before you put your signature on that proof form. (To err is human - I'm uncomfortable around gods.)