When you think of executing SEO plans how do you measure your success? There are lots of ways in which you can calculate your success ratio and can check whether you are moving in the right direction or not. SEO is comprised of many processes and ‘keywords’ is one of the major factors responsible for your SEO plans.
In regards to search engine optimization there is only 1 true way to measure success: rankings. Since Google controls the vast majority of the search engine traffic on the internet, it would be wise to spend the majority of your time delegated to SEO working towards improving your rankings on Google (Note: if you are an e-commerce site you must be careful on which countries you track your Google searches in. If you only ship within the United States, you only need to moniter Google US rankings)
What you need to do is create a priority list of what I call "Money Keywords ". Money Keywords are the keywords with the highest search volume that have the relevency to bring web users to pages on your site. Using free software such as Google Adwords' keyword tool or Wordstream's free keyword tool you can easily determine a given keyword's monthly search frequency as well as get additional keyword suggestions. Once you've compiled your list, begin optimizing and tracking those pages. If you're using the right SEO strategies, over time, you will see your rankings rise. With these increased rankings, you should begin to notice some real ROI (increased sales or traffic) on your time and money spent on your site's SEO.
For some great information on Google's search engine factors, check out this report put out by SEOmoz. http://www.seomoz.org/article/search-ranking-factors#metrics-2
If the question is 'measuring success':
You must be running Google Analytics or something equivalent. You must setup goal tracking, funneling, conversion tracking. For you a 'conversion' may be filling out a contact form, buying your product, signing up for a service. This can all be tracked in Google Analytics and tracked back to the Adword, to the referring site, to the keyword they searched for in organically in Google.
You can get very detailed conversion %'s of the traffic sources that are driving your revenue.
Your SEO plan is not a set once and forget it. So once you have this setup, assuming you are always working your SEO plan, building links, writing great content, guest blogging, etc. and your conversion & revenue that is tracked in Google Analytics continue to rise then that is measuring success.
Metrics for SEO can include:
One bottom line I pay attention to is quantity of new traffic and what sources people are coming from. Inevitably, you want people visiting your site who will buy your product or have a meaningful interest in the site.
In keywords, there is no monopoly. A site can be top for few weeks and then be ranked below the very next week. Seo-ing your website keeping in mind the keywords which you think you would be able to justify by updating your content, providing a good coverage, giving your users to comment or even add an answer is good strategy.
You will need to perform trial and error experiments, before you really know that the path you have chosen is going to lead to your desired outcome.
Lastly, understand GOOGLE, be updated about any changes, follow industry standards, continue your research, and be patience.
I would say that your website ranking in searches for your most relevant keywords (SERP) is the most important metric for SEO activities.
Really the only thing that matters is revenues, or equivalent for non-profit.