This is a pretty good article on common grammatical errors, although it oversimplifies the difference between "affect" and "effect." It fails to mention the situations where apostrophes are appropriate to form plurals, but those are so rare that it's probably safest to ignore them. It also doesn't mention exceptions to the use of apostrophes to indicate possession, such as "its" and "whose."
https://smallbusiness.yahoo.com/adv...istakes-even-smart-people-make-174819423.html
https://smallbusiness.yahoo.com/adv...istakes-even-smart-people-make-174819423.html