Search optimization, and so much more
How they will go about improving your ranking is something a good Seo company can properly explain to you. They have good consultants who can explain to you their planned marketing goals for your site. They should not use tricks in improving your search engine ranking but should have specific plans. Read beforehand the web master guidelines of the different search engines, like Google and Yahoo. Then ask them about how they are going to specifically abide with the guidelines and improve your rank.