Working in a performance-based ad network with more than 1,000 active campaigns at anytime, I've seen the tactics that work. Generally, they follow tried-and-true principles of direct response advertising but are adapted to the fact that people online tend to absorb information by superficial browsing.
1. Stand out from the crowd: Getting attention is a major challenge in the oversaturated advertising world in which we live, and no one will respond to your ad if they don't see it. So be bold, be in your face, be different.
2. Make them an offer that sounds too good to pass up: Direct marketers have long understood that it's the offer that makes people "act now and save." However, nowadays, any discount under 50% off doesn't get people excited. Better yet, find something you can offer for free. Try to state the offer in a way that seems to provide tremendous value.
For example, a theme park I once worked with offered to waive $15 off of its admission price to upgrade to an annual pass. By restating the offer as "Buy a day, get a year free," consumers immediately began multiplying their savings by 364 days and came up with the incredible number of $18,200! It was a deal too good to pass up.
3. Assume your audience has ADD: Studies show the Internet is a browsing medium, filled with multi-tasking. So don't make people wait for your fancy Flash animation to play out or have to scroll down to the bottom and read through all the fine print. Get to the point! Generously speaking, you've got about two seconds to state your value proposition and make your amazing offer in order to hook them.
4. Create a landing page designed to do one thing only -- close the deal: Here are a few rules to create a landing page that works to convert:
5. Tell them what you want them to do: If you want people to take a specific action, don't make it a guessing game. Come right out and tell them! (It's incredible how many people don't.)
Of course there's more, but if you keep the above in mind when designing your next online campaign, you'll be well ahead of the curve in your ability to drive conversions.