I've setup affiliate programs for a few really BIG companies. Each time, one of the biggest challenges that I had was really making it appealing to affiliates once they'd signed up.
If we know anything about affiliates, we know they like a quick dollar. We know they'd rather do the easy work, and whatever is quickest and simplest. As such, I like to setup the back end with resources that make promoting the program easy as pie.
My standard setup:
The top 8 standard Adwords ad sizes
At least 10 articles from different industry angles and interests
Pre-written Facebook status updates
Pre-written tweets they can use
A blogging template for releasing the news that they've joined as an affiliate
A free report or small eBook they can give away with their affiliate link within it
Pre-written email templates
From there, I also mention that our team are happy to help write a custom email promo that's more fitted to their list if it's needed. It's shocking how many people take you up on this, and it only takes a few minutes to modify the existing template. However, it's more likely to get mailed if they knew you took the extra effort to put something special together for them. One of the affiliate managers can do this.
I also like to produce a very simplistic Affiliate guide. One that teaches everything we've learned to this point about our target user and WHO buys our stuff. I give them pointers on how Adwords and Facebook and other ad platforms work, what's allowed and what's not. Within that there's usually a link on how to create their own QR code as well for smart phone users and any other creative ways that might help them sell that particular product.