You don’t always need to write flawless English.

Some grammar rules are optional. Others make you look dumb.

Poor grammar undermines your message. Readers will question your intelligence and professionalism. Clumsy English can stick around for a long time warning the world not to take you seriously.

Apostrophes are a danger zone for inexperienced writers. If you are not a confident writer, alarm bells should ring every time you hit the apostrophe key.

Five apostrophe errors to watch for:

1. The greengrocers’ apostrophe gets its name because handwritten shop signs often use apostrophes incorrectly. It’s unfair to single out greengrocers — the mistake is everywhere.

A greengrocers’ apostrophe happens when a writer turns a word into a plural with an apostrophe s instead of the correct plural ending.

For example: Macintoshes and PCs not Macintosh’s and PC’s.

2. It’s when you mean its.

Its is a possessive pronoun — like his or her. It’s is a compact way of writing “it is” or “it has”.

If this bothers you, make a point of writing it is out in full and never writing it’s. Alternatively try speaking the sentence and checking whether replacing its with “it is” makes sense.

And while we are on the subject, there is no such word as its’.

3. Confusing your with you’re. Your is another possessive pronoun. To check think of: his computer, her computer, its computer, your computer.

You’re is a contraction of “you are”, as in “you’re reading a column on basic grammatical errors”.

4. Muddling they’re, their and there. Another common apostrophe problem comes with “they’re” which is a shortened version of “they are”. Their is the possessive plural pronoun. As in; his computer, its computer, your computer, their computer. There is a place. It is the opposite of here. Their and there are particularly easy words to confuse when typing on a keyboard.

5. When to use who’s and whose. Another case of a possessive pronoun that doesn’t have an apostrophe being confused with a verb contraction. Think of: whose computer is that? Who’s using it?

Short sentences are usually best. But not always and not all the time.

Newspapers teach journalists to write a single thought in a sentence. That way the meaning is clearer.

The Economist Style Guide makes a joke of this in its guide to punctuation:

Full stops. Use plenty. They keep sentences short. This helps the reader.

Much as I love short sentences, too many in a row makes writing boring and hard to read. They can also be uneconomical.

As Harold Evans points out in Newsman’s English:

Often it is wasteful to introduce a subject and predicate for each idea. The subordinate clause in a complex sentence can state relations more precisely and more economically than can a string of simple sentences or compound sentences joined by and, but, so, etc.

There’s another reason to use complex sentences in your writing. They add rhythm.

Use too many short sentences and your copy will have a staccato flow annoying and distracting readers. Use too many long sentences and your writing will lack pace. You may lull your readers to sleep.

Most writing is not poetry. Yet the best poets master rhythm. It makes words easier to listen to, easier to read.

A similar logic applies to paragraphs. View them as bundles of closely related thoughts.

There’s no hard and fast rule about the best length of paragraphs. It’s a good idea to minimise the number of one sentence paragraphs you write. As with sentences, vary the pace. Too many consecutive short paragraphs are annoying. Too many long ones are hard work for the reader. Both approaches are difficult to read.

Above all else use paragraphs to make your writing easier to read.