How do I model advertising revenue for a startup?

At an early stage all startups  are usually advised to focus on building a great product/service and  getting an audience. And then revenue will flow automatically. How right  is this concept? Is it advisable not to think about the revenue too  early in the life of a startup? It is extremely important to focus  on your idea and building something people want, but at the same time  thinking about the revenue model (at least a bit) at an early stage is  recommended as well. Don’t divert your attention from the main goal  since a great product is the lifeline of a startup. But it is also  advisable to at least have a revenue model which you can always change  it later on. Don’t rush into monetizing though, monetize when it makes  sense. A startup can have various kinds of business models, the popular ones being; Figure it Out Later/ Ads (Google, Twitter) Market Maker (Paypal, Ebay) Freemium or Subscription (Animoto, http://Salesforce.com) Virtual Goods (Facebook applications) Price Per Use or Copy (MS Office) Another important suggestion for startups is – know your industry model  inside out. It is very important to analyze the industry. Ask tons of  questions and connect with customers and market. Build a belief that  your revenue model will work in the industry model. In case you need any help..let me know Jimmy Startups Specialist Skype ID- jimmy.vinfotech