Let's first look into the main domains we have to cover/consider for a correct SEO implementation, followed by looking into the methodology to use.

The components of SEO

• Technology is about the ways the website has been constructed. Search engine crawlers behave as rudimentary browsers. They don’t handle well flash, JavaScript,… So be aware of a fancy animated website: Are you sure the web crawler will not overlook links, keywords, because their access requires executing chunks of not supported coding?
   
• Content is about the text, the titles, the meta descriptions of webpages. A search engine can not make use of a picture, at least if it is not well tagged. Search engines require text of a certain length in order to grasp the topics treated. So search engine optimization does involve meeting a number of requirements related to text length, keywords used, emphasis on those keywords to let them stand out,...
   
• Link building is about links coming in from other websites to your website (also called in-links, back-links). A search engine will consider this as a vote for your website. It’s ranking (and as a consequence place in the search results) will increase as you are getting more links. Not every link though has the same voting weight.

The process of search engine optimization.

You should differentiate between the onsite and offsite optimization.  Onsite is your website and what is under your control. Technology and content are onsite, whereas link building (in-coming) is an offsite optimization. (Those websites linking in will in most cases not be under your control). Within the onsite part of the optimization, you should perform 5 steps:

• Define your targets.
  What do you want to achieve ? Make sure the formulation is specific and measurable (e.g. matching “SMART” criteria).
   
• Analyze the SEO improvements that can be done (both on-site and off-site).
  You analyze the “as is” situation in case of an existing website. Is your website “search bot friendly” ? What are the current short comings. Draft a plan to address those: What are the keywords to use ? How to apply this on a site structure ? Look at the text material, HTML, server aspects.During this step you should also measure the current popularity, traffic on your website.
   
• Implement those improvements
  you implement what had been identified during the analyses phase.
   
• Measure the result
  Measure and report to see if you get any improvement compared to what was observed in the analysis phase.
   
• Evaluate the impact of your modifications.
  In the evaluation, you look at the impact of the modifications on the new measurements you got. Which modifications where most cost-effective ? Or is there not enough result ? You might have to run the 5-step cycle again.