Sure, the idea is the key element to your writing, but stating it clearly and interestingly, while writing it in a grammatical style that matches your genius, is important. Even if you have an editor, the better you write initially, the more time, energy, and (likely) money you’ll save in the long run.
Smashing Magazine has gathered 50 resources for better writing, including copywriting, dictionaries, references, punctuation and grammar guides, and more.