Most businesses need some kind of strategic plan to keep their prime activity running to best advantage. Some businesses need a business plan to convince the bankers to lend them money. If you plan to earn with your web site you need the business plan.

You have to have answers to simple questions:

1.What do you sell? If you plan only a little earn on placing of any ads - do not hesitate!

2.Who are your buyers or consumers? Don't say me:"Every who visit my site"!

3.What's cost of your site for you? How many do you invest in the web site? Middle price of creation of the business site (only creation, not support) is about $35000.

4.When and how do you plan to back your money or to get money for your work?

5.What're the goals of your ad company? To increase traffic? To increase right clicks? Other?

6.Did you calculate lower and upper estimates what you can to earn if you enter in the concrete banner exchanges, affiliate programs and mailing lists? (From zero to infinity - it's not estimates).

And so on.
It sounds so non-romantic but it's the better you think about it now then you have troubles and disappointment later.
Put simple you must to plan your e-business as any business.
There are many resources in the Web to help you with creating of the business plan. We can recommend you some from them.

If say serious Internet gives big opportunities to optimize business, to increase sales and to reduce expences. For example, GM, Ford and Dymler-Krysler will open online auction to buy car parts. Expert's evaluation of the reduction of expences is about 10%.

MdDonald's invests in Food.com - delivery service.