In 2006, the most active sectors for affiliate marketing were the adult gambling, retail industries and file-sharing services.:149–150 The three sectors expected to experience the greatest growth are the mobile phone, finance, and travel sectors. Soon after these sectors came the entertainment (particularly gaming) and Internet-related services (particularly broadband) sectors. Also several of the affiliate solution providers expect to see increased interest from business-to-business marketers and advertisers in using affiliate marketing as part of their mix.:149–150
It's especially true now that the big media players are finally waking up to affiliate marketing (NYTime buying WireCutter and SweetHome) and BestReviews (which was already an epic product review site in it's self due to the fact they built their own 10,000 sq ft testing lab) being acquired by Tronc (owns the LA Times and half a dozen more publications).
When I used to write product reviews, I used to include just one affiliate link. For some reason, I thought that a single link would be enough and I didn’t want to run the risk of annoying readers with more links. However, one day it struck me that the reviews I was writing were quite long and by the time people got to the end of them, the link to Amazon was no longer visible.
My intent isn’t to make this Wealthy Affiliate review yet another digital sales pitch. As I searched for Wealthy Affiliate reviews, I noticed the vast majority of them are very one-sided, don’t offer any other options, and are simply biased sales pitches from affiliate marketers trying to make a buck. So, in MY Wealthy Affiliate review, I’m going to do things a bit differently. Here are some of the topics I’d like to cover…
You can use affiliate links after the fact. You don’t have to decide upon building a WordPress site that you’re going to optimize it with Amazon affiliate links. You can decide down the road that you want to give affiliate marketing a try and, consequently, revisit old content, embed affiliate links within it, and start generating revenue that way--especially if your old content is finally starting to take off.
Find a profitable niche. Starting with your interests, write down as many niche ideas as you can. Think about topics people might search online. Ideas include passions (like surfing or body building), fears (like spiders or speaking in front of crowds) and problems (like getting out of debt). Do keyword research to see it others are interested in the topic. Find out if a domain name is available that matches the keyword 100 percent. 
Yes, it costs money, but starting any business takes an investment. The key is to invest wisely, be frugal, and make sure you’re investing in the right things. With Wealthy Affiliate Premium you are literally getting absolutely everything you’ll need to start a successful business online. From the training to the web building tools to the website hosting, backup, security, and support – it’s all there in one place at a very reasonable price.
23. Affiliates – There are many affiliate networks, such as FlexOffers and CJ Affiliate that allow you to promote other people’s products and services. You simply put a link or a banner on your page and then you get a percentage if someone clicks through and buys the product/service. You’ll want to select products that are specifically within your blog’s category.This is an effective way to earn money once you have the traffic coming to your blog.
One of the challenges I came up against when writing about cameras regularly was that while a certain percentage of my readers were actively shopping for a new camera, many readers already owned one. In fact, writing a ‘photography tips’ blog means you attract more people wanting to learn how to use a camera that they already own, rather than buying a new one.
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.