The most important aspect of your site is your content. You need excellent content or readers won't come to your site. Spend the most amount of effort on providing great, relevant, and helpful content and worry about the affiliate ads afterwards. Don't compromise your readers with articles that promote ads. Traffic naturally follows such a site and word will spread, generating more money in the future.
You can reach out to your audience on demand thanks to an email list. Create an email list about a specific topic and send out newsletters with quality content. Once you build up your email list, you can send out information about your products, in the context of your newsletter or usual format.
If you are looking to get the most traffic that you possibly can, then you must use as many marketing channels as you possibly can. This means internet marketing channels, including blog, forums and advertisements, as well as traditional channels, like signs and postcards that lead people to your site.