In the same vein, while you want to be generous with your praise, be stingy with your criticism. People have delicate egos, and even a slight word of condemnation can wound someone's pride. Of course correction will be necessary at times, but it should always have a purpose and be handled with care. If someone makes an error, don't call that person out in front of a group. Be discreet, be delicate. Consider offering up a compliment sandwich — a deliciously effective strategy that involves dishing out praise before and after a criticism. For example:
That newsletter template you sent over looks great, good work. So it looks like there were a few numerical errors in that recent report you sent over — just be sure to double check those numbers. I also wanted to tell you to keep up the great stuff you've been posting in Facebook — I've been seeing a big boost in engagement.
Your goal should really be to get the other person to recognize the mistakes without you pointing them out. Even in the example above, you could simply say, "I saw a few numerical errors in that recent report you sent over," and wait for a response. If the individual responds apologetically and promises to try harder, you don't need to drive home the subject. Tell them not to worry, that you're sure they'll get the hang of it, and move on. The less finger-pointing, the better.
Another strategy for diplomatically dispensing corrections is to begin by discussing your own mistakes before digging into someone else's errors. Ultimately, aim to be always gentle with criticism and only offer it when it's truly needed.