Here’s a quick Google Analytics tutorial on how to see if the number of keywords on your site that result in visits each month is increasing.
The reason you might want to take a look at this number from month to month is that, ideally you’re going to see an upward trend in the number of non-paid (organic) search terms your site is receiving traffic for over time.
Typically, if you’re adding content to your site regularly (easy if you have a blog as part of your site or your site is built on a blogging platform such as WordPress.org) then you should see a steady increase in the number of keywords that are resulting in visits to your site. What this shows you is that all that blogging is potentially paying off. ( I say potentially because traffic without some type of conversion is pointless and worthless!)
To track the number of keywords your site is receiving traffic for, open up Google Analytics ( you do have an analytics account right?) and click on Traffic Sources/Keywords on the left hand menu.
Then, at the bottom of the screen on the right, you should be able to see a number randing from 1 to XXX. The total will be the number you are looking for.
If you adjust the report to show the current month, then last month, and then switch to the month before last, you should see a steadily decreasing number as you go back in time, which means the total number of keywords your site is ranking for is increasing.
Now this won’t always be the case. It is possible that certain terms your site ranks for received more searches in a given month, especially if your business has seasonal elements to it. But for the most part, assuming you’re regularly adding content, you should experience a rise in traffic and a rise in the number of terms that bring in that traffic over the long term.