I think it's wise to invest in a responsive website that will automatically refit and optimize itself on any device. That's very expensive though, especially if you're paying a developer to do it for you. It's also good to have fast loading speeds and well written, engaging content. Ads and affiliate links provide avenues to make money, but they won't help without an audience. In my experience, affiliate links and ads don't require much time or effort. Amazon made it harder to earn when the pay structure changed, but it's still easy to maintain.
I'm anxious to see what others here say. I bet we'll see some fantastic ideas!