There is a big difference between optimizing your site for keywords and making it search engine friendly. While one of the first steps in the optimization process should be focused on ensuring the site is search engine friendly, sometimes we tend to want to jump right into the keyword optimization because that’s how we “see results” in the search engines.
Even though an SEO may do all they can to make a site search engine friendly early in the optimization process, some issues will only be uncovered over time as the engines begin spidering and indexing the website. By keeping an eye on performance we can often find indicators that something may be wrong. With that hypothesis, the SEO must delve into research mode to uncover what, if anything, is creating problems for the site.
There are a number of individual issues that you can keep an eye on. Some issues can easily be fixed at the beginning of the SEO process, others are fixed as pages and keywords get optimized, and still others can only be uncovered later as time passes. Each, however are important to ensure your site remains as search engine friendly as possible.