Many affiliate programs will often run promotions with good discounts or giveaways that might be attractive to your audience. For example, if you're an Amazon Associate and the site have a big Holiday Sale, it would be the perfect opportunity for you to promote discounts to your website visitors. This is a great way to promote your offers while also providing good value to your audience.
The problem with affiliate marketing, like many other home business options, are the so-called gurus and get-rich-quick programs that suggest affiliate marketing can be done fast and with little effort. Odds are you've read claims of affiliate marketing programs that say you can make hundreds of thousands of dollars a month doing almost nothing ("Three clicks to rich!"). Or, they suggest you can set up your affiliate site, and then forget it, except to check your bank deposits.