One should think about their skills, hobbies and basic daily habits as well. Do you like to cook? Be a personal cook or dinner parties. Baking? Make wedding cakes or cupcakes for weddings/special events. Do you enjoy cleaning? Trying going to banks/repo companies and ask if they are in need of a repo cleaner or market yourself as a all-around cleaner. Know how to mow a lawn? Get paid to do it in your neighborhood. Sell products from large companies – Jewelry in a candle, Sentsy, Health and home products – etc.
I never advocate relying on affiliate income as your only form of revenue, or starting a blog with affiliate sales as your only monetizing strategy, because for most bloggers it amounts only to pennies, maybe dollars, and even that isn’t consistent. Sure, you might earn a few bucks here and there or a credit to put toward a service you use regularly. While every dollar’s welcome, of course, and this type of affiliate earnings can supplement other income, it’s not enough to support a family.
The topic you choose must have enough depth that you can create a lot of content for it. This is important for building an authoritative site, for search engine optimization, and most importantly, for the end user. If you don't have enough content about a topic, you're not going to be taken very seriously as an authority on the topic and it's unlikely you can convince someone to make a purchase from you.