SEO should be a core tactic in any marketing strategy. While it might seem difficult to understand at first, as long as you find the right course, book or audiobook, and devote your time to learning, you'll be in good shape. Considering that there are over 200+ ranking factors in Google's current algorithms, learning, digesting and successfully implementing good SEO tactics is essential to the success of your website or blog.
Affiliate marketing is the art of marketing products, services or information for others. It doesn't require that you ever house or warehouse a single thing. But it does require that you have an audience to market those things to online. Without that audience, whether it's through search engines like Google or social media channels like Facebook, you'll find a difficult time with affiliate marketing.