I would be careful with giving away too much too early. High rewards means everyone and their dog will send in articles and sometimes the dog's view on playing Lawtia will be the best of the lot. This might seem like a good idea, but the editors will have to wade through all the cr- errm, low quality articles to find the diamonds.
I would personally only reward a consistent stream of high-quality articles that are placed on the site. I would be very careful with awarding Gran, so I would start with a small article-writers only avatar upgrade, such as nerdy glasses or a flipbook
. A nice status symbol that shows everyone that this person they're playing against writes articles. After that, a slowly increasing amount of Gran for each article after the first to an upper limit. For example, 5 gran for the second article, 10 for the third, 15 for the fourth and 20 for each one after that. Giving writer-only Avatar upgrades seems like a very good idea, too.
Yes, that's not a lot. But people who want to write and have insights to share are usually enthusiastic enough to do so on their own. My personal experience learns that they need mostly recognition, of which monetary rewards are just one option.