Chapter 6 of Kilian's Writing for the Web talks about writing web content for corporate websites. While a bit dry, this chapter is useful because if you get hired to write web content, it's probably going to be for a business. Most businesses, especially small or single-persona ones (like an author/artist/crafter), will require less rigidity than corporate websites, but the principles are the same.
Kilian's main point is that you can't just throw ad copy at website viewers and expect them to get anything out of it, come back to the website, or care. People don't like to be harassed with ads online any more than they like it in person, and if the website only tries to sell the product, it's just a big ad. You need content that engages the reader, anticipates and answers questions, and gives material that the reader seeks or finds interesting - and to provide enough information for people to buy the product or use the company.
Here's pretty good example: The company site for Pierce, a fire apparatus company. They don't just have a list of trucks you can buy - they have behind-the-scenes webisodes about how the trucks are constructed, community information, social media integration, etc. The website is well organized and easily interacted with. I don't really like the surprise fire truck, but it's definitely interesting.
I've found, in my ridiculous amount of time spent browsing the web for no apparent reason, that the biggest mistake people make with corporate/business websites is assuming that all their viewers are morons. "I'll just make it so they can't see anything else until they watch the infomercial. Then they'll definitely want to buy our Widgets!" Or, they'll laugh and close the window after 10 seconds, and assume your company is a hack job desperate to make sales.
A good way to make corporate or business websites not fall flat is to make them interactive. You can easily integrate sharing with AddThis (which adds a button for just about everywhere you can share content), add comment forms so readers can share their opinions, allow reviews of products, feature users of your product, add a search bar so users can easily find what they're looking for, add contests or giveaways, etc. Many websites are integrating frequent user perks and rankings. For example, JINX, a gamer clothing company, lets users 'level up' by interacting on the website and earn 'gold' they can use for discounts on products.