Develop web strategy for our clients multi-niche website/blog

We are looking for a consultant who can help us with a Web strategy. We are setting up a multi-niche blog for a client. The blog will focus on music (hiphop), dj artists, fashion industry, celebrity news, music events in dance industry. The site will also have a store for books that they are about to publish. The client asked our advise to come up with a strategy that can make their website a success. They expect advise for category structure, keywords to target etc. They already hired a webdesigner to customize their genesis wordpress theme, but we might be able to convince them to give that task to us as well. Do you think you can help us defining a web strategy for our clients multi-niche website? Please contact me ASAP. In the first phase I expect a price estimate and your suggestion how to approach this?