Don't you love that term "serial"? Since I hear it most often with the term "killer", that might explain why I dislike it so much. But seriously. When I was in graduate school, my use of the serial comma or more accurately the lack thereof, was constantly being corrected. And here is why. It works differently in Irish English. In "my" English the following is correct:
I love chocolate cake, brown bread, coffee and pasta.
Note: there is no comma after coffee. And this is wrong in American English. In American English you put the comma after all the items in a list. Or as I like to think of it. Put the comma before the and. Look at this example:
This week I hope to meet with my colleagues Margi, Maggie, Patti, and Amy.
See. There is a comma before the and. Although I have lived and written for many years in the US, I have to admit that I still make mistakes. And I am still being corrected. When the English Over Easy site was being proofread, guess where the mistakes were. Yes. You guessed correctly. The wretched serial comma. But I try. I really do. What I think is that my high school English teachers in Dublin must have been fierce indeed for this rule to be so firmly implanted in my brain.
The American Rule: When you have a list of 3 or more items in a list, put a comma after each element including the last one on the list. ( The item that precedes the and)
When writing, make sure to check your spelling, the use of the serial comma, and your tense usage!