Or, How To Sharpen Up Your Writing
If you need a bit of reassurance about your written English, there’s no better place (IMHO) to take a quick refresher course than the Economist Magazine’s Style Guide.
It will help clear up any confusion you might have about Metaphors, Apostrophes, Colons and Semi-colons, and it gives guidance about many common spelling problems, too. Brilliant.
Although it’s not possible to download the whole guide as one file, it’s still worth copying and pasting it as several RTF files and storing them on your hard drive where you can access them easily.