optimize ppc campaign + SEO work

I have just created a sales page website and started a ppc campaign with Google and Overture about a month ago. Despite some recent fine tuning work, which has increased the CTR, my total clicks and sales have decreased, while the cost has increased. I need help in optimizing these campaigns and increasing the sales conversion on the site. This may require the creation of specifc landing pages and some changes in design. Also, I want to start work on generating links and creating good page ranking in the major search engines. If the initial project works out well, this will lead to multiple projects for my other sites. Although the project is listed as small, I would think that this would be renewed regularly, so that we are actually talking about multiple payments. The success rate of the work on the project will define future payments!