One mistake I see time and time again is apostrophes being used incorrectly with plurals. Many people are just not sure where the apostrophe needs to go when referring, for instance, to men, children and people.
The rule is actually pleasingly straightforward. With a singular word, most people know that the apostrophe goes after the thing or person in question for instance Cameron’s government, the child’s bedroom and Wenger’s Arsenal team. It’s pretty straightforward - Cameron’s government means the government of Cameron. Wenger’s team means the team belonging to Wenger.
And it’s exactly the same with plurals. The children’s bedroom is the bedroom of the children. You don’t write the childrens’ bedroom because it isn’t the bedroom of the childrens. Similarly, it’s the people’s decision not the peoples’ decisions. And it’s the men’s race not the mens’ race, because the plural of man is men, not mens.