The word 'GRAMMAR' has a great capacity to frighten people. Many otherwise sensible people worry far too much about their grammar.
As a rule, you're likely to make grammar mistakes for just three reasons:
- you wrote a sentence that was too long
- you have a few bad habits
- you stick to 'rules' that are now out of date, or wrong, or variable.
Most grammar errors in business and academic writing occur in long sentences. So here's the best tip of all: keep all your sentences under 21 words. In a short sentence it's comparatively easy to control the grammar.
Who cares if you can't tell a gerundive from a geranium? That esoteric knowledge doesn't improve your writing one jot. Think more about writing clearly, and less about grammar. You can usually dodge the danger zones by rephrasing.
You need to know just enough grammar to:
- make a good impression
- avoid annoying people who do understand the niceties of grammar
- convey your message clearly, without ambiguity.
The following errors are very common, and they get noticed. Do you habitually make one or two of these errors? Then you just need to change one or two habits. Is that so hard?
- Runaway sentences
- However in mid-sentence
- It's instead of its
- Redundant apostrophes
- I instead of me
- Inconsistent items on a list
- Mismatched subjects and verbs
- Mismatched starter phrases
- Ambiguous use of which
Above all, be aware that grammar is not a religion or a fixed set of rules. It's merely a guide to current conventions. Many 'rules' vary according to country, industry, time, and style guide—so follow your organisation's style guide.
(Crash Course in Corporate Communications by Rachel McAlpine has more detail about these common errors. The book is now being radically revised to reflect business writing in the digital workplace.)