Speaking for the PvP side of the house, one of my favorite ways to "teach" - that is, when someone fires back at the generally good advice I give or perhaps aggressively wants to stick to a basic strategy I know won't be enough in the given situation, is to literally hand them the reigns.

"Okay, you're the shot caller now. Lead us to victory."

Some, very few, actually rose to the occasion and managed to make good calls, or at least figure out what I said/was doing/continued to do was actually good strategy. Others. . . well, didn't. And while sure, it's cruel of me to put all that heat on someone's head, it teaches them that if they want to take the lead, they better know the weight it carries. You don't always have to be right, but you'd better be ready to own up to it.

That being said, it needs to be noted that someone trying to step up and help guide or offer advice isn't just some know-it-all meanie trying to ruin everyone's fun and have it all done "their" way. Sometimes, they truly just know what you're doing wrong and how to fix it, and are offering advice on the fly rather than a Mr. Happy-length guide on it.