Retargeting is the new mailing list. It allows you to advertise without intruding on anyone's inbox. It can easily add an extra 40% more revenue to your bottom line.
Retargeting doesn't require much of a budget to do. It's not like media buying, where you pay by the impression, and have your display ad show up on a particular website 50,000 times.
Retargeting is cookie based. So you're not advertising to the masses. You're only advertising to those people whom already have your cookie on their computer.
For example, on my landing page, there's a cookie for the affiliate program and a one for retargeting. Sometimes the prospect clicks my link to the merchant's sales page, buys the offer and I get a commission. Other times they hit my lander and bounce back to search results. But it doesn't matter, the cookies are set.
I then display retargeting ads as the prospect continues searching down the top 10 organic search results. This allows me to retarget early in the prospect's research and info gathering stages, before they made a final purchase decision.
All you need to do is search for the keyword phrase that you are advertising on. Note the sites coming up in the organic results. Then use a retargeting service to search for them, to see if they allow ads. If they do, use the retargeting service's RTB platform to place your retargeting ads on these top sites.
In addition, retargeting using RTB networks allows advertisers to sneak into the Google content network, which is sort of a 'back door' with a lot less rules and cost than having ads appear on Google's search results. These network ads appear on websites attempting to make money with AdSense, but they are still contextually related to my original PPC ads.
Retargeting can also work well for selling items related to the original search. For example, retarget people looking for jobs with resume writing services. Retarget people looking at travel with luggage, or pretty PDF downloads of tourist destinations, with your affiliate links inside.
So rather than always retargeting with the identical thing someone searched for, like bow ties, retarget with dress shirts. Sometimes being subtle works better and it's not so obvious that the person is being retargeted.
The bottom line is that retargeting works. It's a very affordable way to have your display ads appear to customers and prospects that have already clicked your ads, or visited your website.
The classic definition of behavioural economics is to gently steer people toward certain decisions while still leaving them free to choose.