As you become comfortable with the affiliate marketing process, you can consider both specialized (e.g. fly fishing) and broad (e.g. weight loss) niches. Don’t forget to track your marketing metrics! They are usually provided by your merchant and/or affiliate network. This way you'll be able to know which products your audience are responding to and which ones aren't generating any profits for your business. This is especially important if you are investing into paid advertising to drive traffic and promote products as an affiliate...
Are you a professional in a field that can help answer questions for people looking for your expertise? Websites like JustAnswer and LivePerson match you up with people looking for answers to technical or professional questions. You can make money online by simply answering these questions and providing the right information to people based on their individualistic circumstances.
Sign up for a reputable affiliate network: Aside from Amazon, there are dozens of large reputable affiliate networks, such as Share-A-Sale, Clickbank, and Skimlinks, that specialize in connecting you with merchants who are looking for affiliates to sell their products. They charge relatively low commission fees for the privilege of connecting you with merchants, and the merchants on these sites tend to offer much higher commission percentages or set dollar amount payouts.
Don’t exhaust all the information about the product with your link. Offer enough information to your readers so they know what the link is, but I don’t recommend giving too much detail on your own site for a two reasons. First, product information, like price, often changes. If you mention the price on your site and someone clicks over and finds a different price, it’s confusing. Second, many times, the product details and features are better explained by the makers of the product. It’s best to stick to your own experience on your site.
One of the cool things about Google AdSense is that it's so easy to get set up. If you have a blog or website, you can sign up for a free Google AdSense Account. From there, Google will give you a unique code that you will paste onto your website. Google takes it from there, tracking your page views, traffic, and earnings on your behalf. There is no upkeep or maintenance to get this thing going, which makes it a no-brainer if you have a website already.