Measuring Sales Value and Volume
Depending on the length of your sales cycle and the sales tracking software you use, initial sales value and volume can be difficult to track, but it's often worth it. Initial sales value will show you which organic keywords generate the largest sales, while initial sales volume will show you which keywords generate the highest quantity of sales.
If you're working with an ecommerce website, you can easily track this information in Google Analytics by setting up the ecommerce tracking. It's not too difficult to do and can give you great insights into which keywords generate the most initial revenue.
If you're not working with an ecommerce site, though, you'll need to be tracking sales on the backend through a database, preferably a CRM system like Salesforce.com. To track sales to the keyword, I typically add a custom field to each lead record: keyword.
The next step I take is to include a piece of code at the top of every page of a website that captures the organic keyword and the referrer when the visitor enters the site. Because organic visitors can come in via any page on the website, the code must be placed on every page of the website. When a visitor comes from an organic search engine query, the query can be found in the referring URL. In Google's case, the keyword appears in the "q" value in the referring URL and keywords in a phrase are separated by "+" signs. If the referring URL contains a q value and, for instance, the domain "google.com," then you know that the visitor came to the site via Google organic search. Add a cookie for both lead source and keyword. Then, when the visitor converts, download these values and enter them into your form via a hidden field, which will update your CRM lead record. Voila! Now you can track what direct impact your organic search has on sales.
Lifetime value is an often-overlooked, but important, measurement. While initial purchase may not be high, some customers may spend high values over time. Like initial sales value and volume, lifetime value requires a backend sales tracking database to track the data over time.
Depending on the length of your sales cycle, look at lifetime value once a year or more -- the longer the sales cycle, the longer the period between times to review lifetime value. Tracking lifetime value to the keyword level will help you indicate which keywords are your historical "money" keywords over time.