Let no one tell you that email marketing is dead. An email list is crucial for every affiliate marketer. You can start building up your email list with a lead magnet (like the information products mentioned previously) or even just by encouraging your audience to sign up for your updates. You can then push your content to this audience via email and also direct them to your affiliate offers. Don't be sleazy about the sales, but if you build up enough trust with your email audience; when the time comes, they will not mind purchasing a product from you.
Next, you’ll want to pick a WordPress theme from somewhere like ThemeForest, Elegant Themes or OptimizePress. This is the barebones design of your site, which you can then customize with your own branding, copy, and images. That being said, you don’t want to cheap out. It costs less than $100 to buy a theme that will make your website look professional (and you can upgrade to a completely custom design once you get the business going).