Selling graphic T-shirts is big business. Customized T-shirts with clever sayings or graphics are ideal for online sales. Sites like Teespring allow you to sell customer shirts. Teespring’s unique model allows you to design the shirt and get buyers lined up to purchase it. This saves you from the initial investment in stock and the time on processing and shipping orders, though you’ll likely make a smaller profit on each shirt sold.
You may have noticed in my overview of the Amazon Associates site that I left out the mention of the plugin they built for WordPress. That’s because the plugin doesn’t work (at least not well). Luckily, the Amazon Auto Links plugin will simplify the process of finding new and relevant products to promote and creating affiliate links to them--all from within WordPress.
Set up a website. Professional or business websites can also use the Affiliate program. However, they are best used with people who do not sell similar products on their website, since Amazon's marketplace can drive business away. If you have a website promoting different products, a club, a non-profit or a service, then you can recommend quality products on your site and make money doing it.
Analytics are limited. Unlike with conversions made directly on your WordPress site, you’ll be limited in terms of what you can learn about the people making purchases through your affiliate links. While Amazon does provide you with details about clicks and sales, you won’t get deep insights into who the consumer was and what they did on your site before they got to that point that you would with Google Analytics.
Cost per action/sale methods require that referred visitors do more than visit the advertiser's website before the affiliate receives a commission. The advertiser must convert that visitor first. It is in the best interest of the affiliate to send the most closely targeted traffic to the advertiser as possible to increase the chance of a conversion. The risk and loss are shared between the affiliate and the advertiser.
Amazon has spent years perfecting the art of online selling and you’ll learn a lot about online marketing by observing how they do it. They constantly test different ways of promoting products and have evolved their site quite a lot over the years. See what widgets they use to promote related products, watch how they use reader reviews, and see the way that they describe products.