SEO required for multi site collection – long term ongoing project

We are currently in the process of creating a new brand of premium rate psychic websites.
We are now at a stage where we require an experienced company or individual to advise with regards to site plan and SEO.
We have read lots of interesting facts regarding: Location of server, link backs, keywords etc etc and now need a company to look at exactly which of these (plus new ideas) have merit and what will help us attain a high search ranking and maintain it through the longer term.

This is an ongoing project with opportunities to look at other sites within the business and expand the site setup to other business areas.