There are a few key statistics that every website operator selling a product or service should track. Of course, these are useful for other types of sites too, but when you're attempting to sell something, you need to know where to spend your time and/or money to be most effective.
Unique vs New Vistors
A lot of website statistics software, e.g. Awstats, Webalizer, will tell you how many unique visitors you have each day. These are important numbers, but you don't get a good picture from day to day of how many of those users are new, i.e. how many of those users have visited your site on a previous occasion.
New Visitors are certainly a part of the unique visits, but you have to track them separately. Why? This number gives you insight into how many people your marketing effort is driving to your site. If you have 100 unique visitors each day but only 100 unique visitors for the month, you have a pretty good retention rate on your visitors but certainly not a very good acquisition rate.
One way to track new visitors programmatically is to test for and set a cookie upon a visit. If you have the capability of doing this, and then storing a record each time you set a new cookie, you'll be able to watch your acquisition rate from day to day. Another alternative would be to find a 3rd party service, e.g. Google Analytics, that provide you with code to place on your page.
Acquisition vs Conversion
Once you have the number of new visitors, you can start to form statistics based on that number that provide insight into the effectiveness of your site. The number of new visitors that purchase a product for the 1st time give you a conversion rate. These two numbers together can provide insight into where promotion money will be most effective.
- Increasing Traffic
There are a number of different ways one could spend marketing dollars to attract new visitors. Assuming that your conversion rate holds fairly consistent, more users ought to translate into more conversions. If you have a pretty good conversion rate, spending money on driving more traffic to your site could be the way to go.
- Increasing the conversion rate
If you are getting a pretty good number of new visitors, but your conversion rate isn't very good, driving more users to the site might not translate into more profit. In this case, it may be best to evaluate how effective your website is at selling your product.