How will the Search Engine Optimization firm work on your site? Are you going to give them access to your server, to where they're responsible for uploading pages and making changes?

Or, will they have to go through a Webmaster, thereby slowing
down the process. Some Search Engine Placement companies like to set up gateway pages on their own server and route traffic to your site. Other Search Engine Optimization firms like to set up separate Web sites on their own server as a means of building link popularity and routing traffic. If that's the case, who will own those gateway pages or sites if you decide not to continue using their services?

When the Search Engine Placement firm owns the pages or sites, if you take your Search Engine Optimization work elsewhere, that firm can simply re-route traffic to another client's site. There's nothing illegal or shady about this-it's just a fact of life. However, you can always choose to negotiate ownership of a gateway page or site in the initial contract.