Although I tend to disagree with nearly everything that Sir Korhan has said at CC, (no need to take offense Matt), I can't agree more
with what he said on the previous page.
Don't worry if you're not that good at writing. No-one expects you to be the next Edgar Allan Poe/Frank Herbert/Tolkien ec. Just write what you want and enjoy it. You will improve over time.
Another thing - don't feel you have to write loads; in fact I sort of dislike too much writing as it simply becomes too much of a task to read it all. Not every mountain, every piece of armour and every movement needs a paragraph of extensive detail. This is easy to avoid if you're doing illustrations as you generally won't have to do much description (pictures speak a thousand words).
You all seem to be focusing on personal preference than helpful tips, but if discussion is the founder of progress, then you guys are off to a good start. Some helpful things that I use are in Microsoft Word. Spelling is automatically checked so that even when you write a word that is of your own making, it gives you a chance to see if you spelled it correctly. I sometimes find myself looking for a word that fits the mood better than one that I've used previously or even a word to keep myself from being too repetitive. The Thesaurus feature is a gift. Don't get carried away with it though, bigger words (or should I say more complex) are not always better. Sentence structure is also critiqued in Microsoft Word. What looks good might not be proper if you are trying to be professional. I sometimes have to override this feature, as it can interfere with dialogue or the feeling I'm trying to convey. One more thing, don't be like me and go comma crazy.
Hope these help.