SEO strategy

Hi, I am looking for a company that can propose a SEO strategy for our website. We are an ecommerce based site selling major brand software products in Canada. Products such as Adobe, Corel, Microsoft, Symantec, Kaspersky, etc.. We are looking to significantly increase traffic to our site, relevant targeted traffic. At the moment we are in most price comnparison sites in Canada and have been doing some minimal PPC through adwords however conversion cost is really high. What we need is someone with online marketing experience that can research our industry, our market and suggest the best seo marketing strategy for what we do. It is imperative that you have experience in this and that your approach in working with clients is tailored for each client versus offering the same package over and over again. Before I commit to any work, I would like a proposal outlining a strategy. This will be mandatory. Thanks.