Ah, they’re tricky little buggers!
An eggcorn is a word or phrase that speakers and writers tend to get wrong because the wrong version (which always sounds a lot like the right version) sort of makes sense. “Eggcorn” is the eggcorn for “acorn.” You can see the sense of it, right? An acorn is a tree’s seed, and a seed is a tree’s equivalent of an egg. Perfectly reasonable.
Some eggcorns show up a lot. It’s not “intensive purposes”; it’s “intents and purposes.” It’s not “tender hooks”; it’s “tenterhooks.” It’s not “a tough road to hoe”; it’s “a tough row to hoe.” And so forth.
Unfortunately, there’s no general rule for fixing eggcorns. They have to be hunted down individually. Your best bet may to find a long list of eggcorns and read it through. Maybe you’ll discover you’ve been eggcorning something. I thought it was “in like flint” for the longest time (it’s “in like Flynn”).
The main thing, I think, is to maintain your sense of caution, never assuming that what you think is right must, in fact, be right. If you have the slightest doubt, just feed the questionable phrase into Google with the word “eggcorn.” If you Google “doggy-dog world” and “eggcorn,” you’ll get your answer right away (it’s “dog-eat-dog world”).
A final thought: sometimes no one really knows which is the acorn and which the eggcorn. Is it “hone in on” or “home in on”? The mystery remains.