If you have built your websites and have drawn some attention then it is time that you can start earning through banner ads; by far the most popular for of advertising on the internet.
If you are thinking naah, it is too early to start, then let me tell you, if you are able to sell your banner space (you have an interested buyer or network) - it's probably never too early. Also - by incorporating banners into your website at an early stage -- it gets visitors used to the idea, and also will improve your final site design.


The problem with trying to sell banner ads early, however, is that banner ads don't pay very much per impression or click. As a result, you need to have a reasonable amount of traffic in order to make any real money with them. Plus, many of the Banner Networks require you to have a certain number of visitors/page-views before you can join them. The number of page-views your site generates in a day/week/month represents how many Banner ads you can display in the same amount of time.


A good alternative to trying to make money right off with banners is to join a Banner Exchange. A Banner Exchange is a site that lets you show your own advertisements on other sites, in exchange for showing those same sites’ banners on yours. The Banner Exchange itself will save some percentage of banner displays for itself, so the exchange ratio is usually around 3:2 (for every 3 banners you display on your site, they will display your 2 of your banners).
 
Hence, banner ads are a very popular method to generate some extra income from a website. Many of the larger sites utilize banner ads as their sole source of income. The downside is that you'll need to generate a lot of page views to generate significant amounts of income... but is a good starting point for many sites. Weigh your pros and cons and invest in this as much as you think will lead you to profits. It’s time you start talking business.