I have a gaming website that has 20,000 daily active users, all from US. They spend an avg of 15 mins on the site and are highly engaged. I've never done affiliate marketing before so is it a good idea for my website? Thanks!
The likely answer is yes, but you'll have to test and work harder to prove the revenue. AdSense is just place it and go, and you get paid, yet AdSense earnings in many markets are not that lucrative, but they are easy.
Affiliate programs are not as easy as AdSense in some ways, because what you are looking for is a buying behavior that your audience has - the type of products they will get - and a way to introduce them, via targeting, to people who are willing to buy.
Some sites just do not have a buying behavior, and because you are in gaming, people come there and stay because they are interested. As others have shared, walk carefully because you could start promoting and causing a negative effect if you have the wrong products and the wrong targeting.
Affiliate programs can work, yet they do take work, more than AdSense, which is why once you find the right products your users love, it can make more than AdSense, but will take some time to figure out what is converting for your specific audience.
Also, if you have Google Analytics set up with newer tracking, you should find Interests and in market segments, which can show you what your users are looking at before they go to your site, and can lead to some product selections based on behaviors, not guesses.
Rather than going through an affiliate bank, I'd look for individuals who create products that would be valuable to your community and partner with them directly. In the digital space, many affiliates offer 50%, so you'll earn a lot more. The products are also more likely to be relevant and high-quality, so your community actually appreciates you sharing them.
You might also consider reviewing products on your blog that are relevant for your readers. We do this on The Write Life, and it works well for us: http://thewritelife.com/resources/
It can be a good idea, if you place the affiliate banner ads in a place they will be clicked on and the companies you choose to affiliate with are highly targeted to your website's audience. I would also encourage you to launch a pop-up email capture box, offering exclusive deals in exchange for their email address. Then you can send email blasts to your subscribers with the coupon codes that the companies you have affiliated with have given you to promote. This can be an effective strategy to generating affiliate sales with your website traffic.
One of the best affiliate marketing sites is Maxbounty.com. They pay for a lot of things including leads. Some of these leads pay over $50! Sign up for maxbounty and when you get accepted, you can place ads on your website or wherever you want to advertise and when someone uses your link to sign up or go to one of your ads, then you get paid. Very simple. Hope this helps!