1) Form the possessive singular of nouns by adding 's. (Note: possessive pronouns such as its, theirs, yours, ours, hers, etc., NEVER require an apostrophe, whereas contractions--it's, there's--do have an apostrophe, indicating what's left out.)
2) Items in a series are separated by commas after each item except the last. Thus, in the following sentence, follow the commas:
My cat ate a bug, threw up on the rug, and fell asleep. (3 items in this series)
My favorite colors are purple, lime-green, fire orange, and charcoal gray. (4 items)
3) Enclose parenthetic expressions between commas. This includes appositives.
Parker, the kid with the skateboard, looks like he's fairly athletic.
Remember: it's parethetic if it doesn't have to be there. If you can safely take it out, like this phrase here in red, it's parenthetic.
Today, we looked at rule 4: Place a comma before a conjunction that introduces a main clause. (This connects us with FANBOYS.)
* More on Romeo & Juliet, Act I, Scenes 1 - 5 later... (We will have a test on Act I on Tuesday.