As far as your experience with website analytics are concerned, name the three data points that are most important to you. Why are these important? How do you go about managing them?
The three most important data points would be those based on a discovery conversation with the website stakeholders. Identifying their goal or goals determines which data points to review, establish as a baseline and measure progress. As I’m sure you know, without knowing the goals or the context of a given metric, each data point could be viewed in variety of ways. For example, an Average Number of Pages Viewed Per Visit of one is more likely to be expected for a lead gen site than an ecommerce site. A low Number of Referring sites is expected if the online marketing focus has been SEM vs SEO. Direct Traffic vs Organic Traffic may vary depending on the SEO efforts and the awareness of the brand (website URL). Any analytic metric can be influenced once the client’s goals are determined.
You mention that you have exposure to SEO. What, in your opinion, is the one mistake that other webmasters make most often?
The predominate factor I’ve encountered is those performing SEO analysis in a vacuum. Meaning the client’s website position in the SERPs is directly related to those websites competing for the same keyword or phrase. Best practice SEO being a given, the way to influence the client’s position is to do enough SEO to be statistically a Position 1, 2 or 3 option in the search engines opinion. Without the competitive research and baseline reporting you are hoping that your version of SEO Best Practices will provide the desired lift.