Search Engine Optimization
With Search Engine Optimization (SEO) nothing is ever guaranteed, so my first rule of thumb is to be skeptical of anyone who does guarantee you specific results. That doesn't necessarily mean they can't do it, but they may just be talking about a specific search for your name or some other obscure search term that you could probably get yourself without much effort. You want to rank high for a term that people are actually searching for. After all the end goal is not to rank high on the search engines, it's to bring relevant visitors to your site. The search engines are continually changing their algorithms which constantly changes their results, so even being number one in the rankings today doesn't necessarily mean that you will be on the first hundred pages tomorrow. There are many sites who depend on search engine traffic who have seen their business plummet when the search engines perform an update.
I always try to build SEO into my designs with good content and using industry standards. I try to explain to my clients that whenever I design a website I do it with the visitors in mind first and the search engines second. That if you can design a site that provides good quality content and easy to follow navigation the rankings will come and remain fairly consistent.
Although I prefer to include the SEO in a new website design I have had clients ask me about optimizing their existing site for a specific keyword(s) and how much would I charge for that. Often the client believes that to get their site to number one at all the major search engines all that needs done is to stuff their content with keywords and to add meta tags (usually stuffed with keywords). Sometimes adding keywords to a title or text of a page will help, but unfortunately, due to abuse, most search engines give little or no weight to meta tags for rankings anymore and "keyword stuffing" can be seen as Spam which can get your site's ranking lowered or possibly in extreme cases banned completely. The other problem with this approach is the site usually doesn't read very well. That makes for an unpleasant experience for the human visitor. The idea is to know and balance what keywords to try for, how to incorporate these into a site pleasingly and what, if any, other factors need to be considered.
The question remains how and how much do I charge for this? My usual rule is to quote a flat rate based on how many hours I believe that I will have to spend to do the job right or a lower flat rate with performance bonuses included. Many times doing the job right it involves completely changing the way a website is structured and that involves more time, resources and money than what is available. I also let the client know that when dealing with the search engines there are never any guarantees. Search engines are very secretive about how their rankings are arrived at and if everyone could easily get to number one then everyone would be number one (for about a second).
What I can do is to provide them with past examples of my work, but as with investments "Past performance is not a guarantee of future results". It does give the client an indication of what they can expect, but pricing SEO is a bit like saying "How much is a car?" there are many factors that need to be considered.