Here’s a discussion of that often maligned—or at least, often ignored—punctuation mark, the Oxford or serial comma. Disclosure: I believe in the Oxford comma and never leave home without a bagful.
However, do note that when you have only two items in a series (a compound), you DO NOT need a comma before the coordinating conjunctions (usually “and” or “but”). So sayeth Virginia. What sayeth you?
(BTW, if you haven’t encountered the Freelancers’ Union, you might want to take a look. They provide support for independent contractors and single proprietors of all stripes!)
Here’s an extra comma, in case you’re out!