While most webmasters constantly make changes to the look & feel of their site, they often forget about the consequences in terms of marketing. Changing the navigation or moving around some links might result in a radical variation in sales, would it be up or down.
For example, since redesigning their site, a couple of affiliates have not only increased their monthly revenues but more than doubled their conversion rate (earning per click). On the other hand, other affiliates saw their sales drop to zero after removing a link that was located in a strategic location such as the home page or the navigation.
A great way to see how design makeovers might affect your overall marketing effort is to look at your affiliate reports. If you spot a sudden change in sales and know for a fact that no external factor is involved, you can be certain that the two events are related, which will allow you to make the appropriate corrections or improvements.