Here's another beginner tip, this time on punctuation. New writers often have problems with punctuation, sometimes without even being aware of them. When I started writing as a teenager, I punctuated intuitively. Since I read a lot, I had "absorbed" punctuation rules without realizing it, so the result was not too awful. But it wasn't  altogether good, either, and the goofs can make a piece of writing jump out as amateurish to a trained editor.

It would be impossible to cover this whole subject in a single post, so I'll just hit a couple common problem areas.

Compound Sentences and Compound Predicates

A compound sentence is two clauses (groups of words that could stand alone as complete, independent sentences) joined together, usually with a conjunction like "and" or "but":

John disliked red wine, but Elise loved it.
I had traveled two hundred miles in search of the treasure, and this was my reward.
It was rainy out, so Sarah opened her umbrella.
I didn't notice him leave; only the rustle of the curtain testified to his departure.

In all the examples, each clause has its own subject and predicate. In each case, you could rewrite them as two separate sentences by removing the conjunction:

John disliked red wine. Elise loved it.
I had traveled two hundred miles in search of the treasure. This was my reward.
It was rainy out. Sarah opened her umbrella.
I didn't notice him leave. Only the rustle of the curtain testified to his departure.

All of these rewrites make perfect sense.

OK, so how to punctuate compound sentences? The rule is simple: use a comma before the conjunction if there is one. If there is no conjunction, use a semicolon. Never put the comma after the conjunction. The comma isn't optional:

It was rainy out so Sarah opened her umbrella.

This will strike an experienced reader or editor as a disorganized stream of words, not a correct sentence.

Be careful, though. Not every "and" or "but" marks a compound sentence. If there is only one subject, it is a compound predicate instead:

John took a puff on his cigarette and stepped on the gas pedal.
The rebellion had suffered many setbacks but was in no danger of running out of new recruits.
I left the two to their quarrel and poured another glass of wine.

Commas aren't used in compound predicates. (Occasionally, a comma may be helpful in a compound predicate to emphasize contrast or for clarity if the wording becomes complex. These are exceptional cases, though.) Mastering the difference between these two types of sentence goes a long way toward keeping punctuation problems at bay.

Introductory Phrases

Here's another common situation where a comma is needed. An introductory word of phrase tells the time, place, or circumstance of the main rest of the sentence, or qualifies it in some way. (Did you note the comma in the compound predicate of that sentence?) Introductory phrases can also serve as transitions, showing how the sentence relates to the previous one.

When he had finished his tea, Erik turned his attention to the day's headlines.
However far you travel, you take your demons with you.
Without realizing it, I had blocked my only escape route.
Walking along the beach, Jen and Alice saw the storm gather over the waves.
Well, that's how it seemed at the time.

You can recognize these introductory phrases with a simple test. If you omit them, what remains is still a clear statement of the action of the sentence. You just lose some context. The comma is needed in all these cases to let the reader know when the main sentence begins. Without the comma, you could end up with very confusing strings of words like this:

While we were eating the cat played outside.

At first take, it sounds like the cat was being eaten!

When the introductory phrase begins with a preposition, the sentence can often be reworded with the prepositional phrase at the end:

Erik turned his attention to the day's headlines when he had finished his tea.
I had blocked my only escape route without realizing it.

The first is awkward, although it is grammatically correct. The second is fine and might be preferable in some situations. Note that the comma is not used when these prepositional phrases come at the end of the sentence.

Next

Finally, if you find yourself in a punctuation tangle, consider rewording. Breaking a complicated sentence into simpler sentences will often improve the flow of the writing. I have a nasty tendency to write overly complex sentences myself, a consequence of being immersed in technical writing in the sciences all my life. When I write fiction, I often produce a lot of wordy sentences in the first draft. I force myself to be ruthless with them when I revise.

Although some punctuation rules are widely observed, there are variations between countries, and even various conventions used by different editors and publishers. Also, creative writers sometimes bend the rules, especially when writing in a character's voice. This does not mean, however, that writers should indulge their whims. Inconsistencies in punctuation undermine a writer's credibility. Every serious writer should own a style guide, learn it thoroughly, and follow it with care. Make exceptions only when creatively necessary, and only with full knowledge of the rules.