"When, the heck, am I supposed to use commas?"
I'm glad you asked! Well, rather, not really...you see, that question requires a very complicated answer in order to fully inform you (but as a side note, there should not be commas separating "the heck" from the rest of your question...read on to find out why). However, I will now attempt to cover the basics—general rules of thumb that you can use without wading through grammar jargon and endless rules. At some point, I will do a few more technical posts on commas...just not yet. :)
- Consistency matters the most. More than where, more than how many, more than any other comma factor—readers will notice your consistency. Even if you don't know what you're doing, if you use commas in a consistent fashion, (most) readers will think you have a reason and they just don't know what it is.
- A comma is meant to separate ideas. Think of the comma as a friend of the reader: it helps readers know when one idea ends and another begins; it helps readers know when to take an imaginary "breath" before plunging into the next thought. It organizes lists, descriptions, and independent ideas so readers "view" them independently. This is also why there should not be commas in my reader's question; if you were to ask me this to my face, you most likely wouldn't take a breath before and after "the heck."
- Read your writing out loud to find missed commas. If you take a breath before going on, chances are that some form of punctuation should go there (a period at the end of a sentence; a comma inside a sentence). If you don't take a pause, there probably shouldn't be a punctuation mark. As an example, read point 1 above out loud; you'll see you pause every time you come to a comma; now imagine those sentences without commas—much more confusing, right?
- Finally, err on the side of fewer commas. I almost hate to say this, because I am a huge fan of commas, but if you're shaky on when to use commas, try to use as few as possible. Generally, you won't need as many commas as you think you will, and too many commas will make your writing choppy and hard to follow.