When you measure the success of your SEO efforts, search engine rankings are not the only KPIs you should be focusing on. Below are some important metrics you should be using:
Organic Search Traffic Volume – This is the metric you should be tracking monthly, because after all, the goal of SEO is to attract visitors to your site organically via the search engine. Since Google has encrypted all keyword referral data in Google Analytics (citing the reason of privacy), you should instead be focusing on whether organic search traffic volume has increased this month compared to last month.
Quality of the Traffic – Careful analysis is needed to determine the quality of your visitors, and there are some metrics which you can use, including Pages Visited, Bounce Rate and Average Session Duration. For example, if a page has a high bounce rate and the average session duration is low, this is bad news as it means that a high percentage of your visitors have left your site after viewing just one page (a bounce), and left very QUICKLY. This may mean that the page content is not providing your visitors with what they wanted, and so this will be something you need to work on.
Conversion – In Google Analytics, these metrics are specified by setting up goals. Conversion tracking may include phone calls, contact form submissions, quote requests etc. So the total goal completions from organic search traffic is a useful metric for reviewing your campaign. Conversion rate is another metric you should be looking at, and this is the percentage of visitors that actually convert of has completed a specified goal.