SEO companies come in all shapes and sizes. You've got your solo SEOs that either a) do everything themselves and/or b) sub-contract out many aspects of each campaign while maintaining a tight control on the quality and results of the project.

Then you have your big SEO firms that employ 20+ employees that handle various aspects of your account. These firms can often turn into SEO factories and can lack the ability to treat each client individually, because everything is done in bulk.

A third SEO firm is a smaller firm that employs a small handful of employees and may also sub-out a few various aspects of the campaign, but overall each client is treated with a personal hands-on approach with most of the campaign handled in-house with strict quality control measures.

The perfect SEM firm needs at least one (or more) of the following:

• Project Manager
  The project manager is responsible for overseeing every aspect of the SEM campaign. Their job is to ensure that each aspect of the project is given to the appropriate person to complete and double checks all work to ensure that the highest standards are met before it is passed on to the client. The Project Manager is the primary contact with the client and bears the responsibility of ensuring that the client knows that their campaign is a top priority.
• Lead Search Engine Optimizer
  The Lead SEO spends much of their time doing nothing but research. Researching SEO trends, search engine functionality, patents, white papers, etc. Their job is to ensure that they stay on the cutting edge of the technological changes that are coming down the pike. It is also their job to take this knowledge and apply it to each and every optimization campaign. From keyword research and organization to implementation of the on-page optimization factors. The lead SEO also overseas any optimization techniques implemented by sub-seos, link builders, etc. that may be managing the day-to-day tracking and tweaking of any site.
• Search Engine Optimizer
  All other SEOs work directly under the lead SEO and work to implement his "vision" of the perfectly optimized page. Each should do their own research and knowledge building but any implementations should follow the outline presented by the lead SEO. These SEOs should be responsible for the day-to-day optimization changes, as well as continuous research to ensure that any client's site's are free from potential currently unknown search engine roadblocks.
• Coder/Programmer
  While all SEOs must have a significant knowledge of HTML, XHTML and CSS coding, it is helpful to have an additional person who is primarily responsible for the code optimization aspects. Optimizing and streamlining code can be a significantly time-consuming process, especially when ensuring each optimized page has full cross-browser compatibility. When not working on the optimization code, such a person would be working on developing and improving in-house tools, reporting systems, as well as publicly available tools.
• Copywriter
  The importance of a professional copywriter cannot be understated. SEO methods that simply take your keywords and try to place them into text are becoming less and less effective, not only for search engine placement, but for ensuring a quality user experience. Each optimized page should have its content re-written by a professional copywriter following project-specific keyword guidelines established by the lead SEO. SEO copywriter should have a marketing background and experience with ad testing and writing press releases, as well as general article content.
• Link Researchers
  This may be controversial to some, but it is increasingly important to have full-time link researchers continuously working on each campaign. Link researchers are responsible for seeking out other quality and related sites to do one or more of the following: Link to important sites, request links from important and/or related sites and submitting links to quality relevant directories.

As SEO becomes more marketing oriented, many more positions must be added for a firm to properly service their client’s needs. Speaking strictly from an SEO aspect, these jobs are each an important aspect of achieving success with you optimization campaign.