Much of advertising you see on web is of "here today, gone tomorrow" genre. Some think they can throw up a web site or join an affiliate program, and they will have to buy a wheelbarrow to carry $20 bills in from their mailbox. Well folks, that "ain't" case.
There are a number of forms advertising can take, and let's first discuss ones at opposite ends of spectrum.
Sales Advertising is designed to sell a specific item immediately. A good example of this can be found in your newspaper supplements, advertising coupons for specific food items in a local store. On TV, an ad for a particular CD is another example. They are trying to entice you to purchase a specific product within a specified time. Most of these ads are "price driven", and if you take advantage of their offer, you will realize a savings.
Institutional Advertising is not trying to sell you something specific. It is used primarily for "name awareness" and when faced with a purchase, they hope you will remember their name. When IBM airs an ad, you will seldom see a specific product for sale. When you buy your next computer, they are banking on you remembering their name, and will purchase their product.
Most of non-professional advertising you see on web is neither. They are usually trying to sell something specific, but give no reason to buy from them at this time. Affiliate programs are big offenders here. If I am going to get involved in something like "Six Figure Income" program, why should I do it with you. There are thousands of people trying to sell this program, and many are not making anything, but some are. The real question here is why.
If you are going to be involved in an affiliate program, you must give people a reason to buy from you. Obviously, if you provide a bonus that others don't, they now have a reason to get it from you. Take a lesson from some of Internet Service Providers. Many will give you a free month if you recommend someone, and they remain as a customer for three months.