I own an online business and its a lot more work then you would ever expect. Can be very rewarding, however, a lot of work.
A couple of things to realize:
1. Having a great website does not make it automatically successful. It has to be advertised properly.
2. The more unique content that you have, the better. You will earn higher rankings on the search engine. Don't try to take a shortcut and just copy material because google recognizes copied material and won't help you in the rankings...
3. When you do write content, include top ranking key words within the content that people would actually search for in google to get your product.
4. Don't include more then about 5 or so keywords per page. Google is on to that trick...
That's all I got for now, if you have other questions, let me know...