Excerpted from my contribution to Blog Design Fatalities by author Ryan Jackson.
It depends on how the blog interacts with your sales, I suppose. Say you are an online retailer of Sci Fi DVDs. You could include an “Ask the Expert” type blog, and perhaps a news blog. Within these blogs, you could create direct links to pages where related merchandise could be purchased. For example, if you are announcing a new cast addition to Battlestar Galactica, you could link the words “Battlestar Galactica” to a page of DVDs from previous seasons. Or, if you are answering a question regarding Firefly, within your answer you could link key terms like character names, or references to specific episodes, to the DVDs they appear in.
Design wise, you could emphasize these links in a bold color, and perhaps add a hover style that changes the color of the background, so it is very obvious to a user that the word is a link.
If you are using your blog to sell items (and don’t have a separate store) the best advice I’d have is to create a purchase button. Make it obvious that this is what needs to be clicked to buy, and have it go directly to a screen where you can make a purchase. Confusing graphics, bad placement and/or too many clicks can lose a sale. Don’t be afraid to experiment — on our front page, we actually experimented with several locations for our sign up button before determining the best conversions in terms of placement.