Misuses in writing that involve apostrophes (or the lack thereof) scream for attention. "I really like you're poem," for example, or "Its really tough to know which word to use."
Lots of times, an error like using "you're" for "your" is committed in the heat of writing, in part because the two words are homonyms. When you, the writer, go back and edit you probably see "your" where you wrote "you're." (Or vice-versa.) You end up looking stupid when an editor reads your manuscript--or at least wincing when you catch the error later. One way to cut down on this sort of problem is to use fewer contractions. Statistically, you'll commit fewer errors involving contractions.
Misuse of 'its" or "it's" occurs because people forget which form they're supposed to use. There is an easy solution. Remember that a contraction always wins out over a possessive, like a flush over a straight. Then do a search in your manuscript for every occurrence of "its" and "it's" and make sure each fits the "winner" rule.