Anne Gracie shared the think to the University of Bristol. They have exercises where you can practice your grammar! Yes, I actually find this kind of thing fun. No snickering.
Excellent check list from Writers In The Storm blog:
The Oatmeal shares a brilliant bit on the use of semicolons, apostrophes, who vs whom:
There are more. If I taught school, I would so have these posters in my classroom.