As writers, we need to remind ourselves that we are in a world populated by people who love the English language. Unfortunately, many of us are judged by those people (agents, editors, publishers, reviewers) based on our grammar and punctuation. For the most part, most of us are pretty good at grammar. Where we fall down is in the use of punctuation, in particular: the rules for the use of commas.
Personally, I don’t think there is any set of rules that goes stale as fast as those regarding the proper use of commas. The good news is we can get up to speed on them without much effort. We can do well using them correctly for months. Then we start to slip back to old habits, or we start to forget what those rules are. And this is understandable. There are a lot of rules about using commas. And it is really hard to remember them all for any length of time.
So what do we do? Find places to brush up on your punctuation online, at local adult education classes or from your favorite textbook. Do this often. I find about every 18 months works well. I want to suggest one fabulous book. Get it. Keep it where you write and take pride in dog-earing the pages. It is:
The Least You Should Know about English: Writing Skills. It is written by Paige Wilson and Teresa Ferster Glazier and published by Thompson/Heinle. Warning: It is expensive, even in Kindle Edition.
You can also find some great guidelines online — for free.